The investigation of reaction kinetics is the key to understanding the nature of reaction processes.However,monitoring fast photochemical reactions by mass spectrometry remains challenging.Herein,we developed an optic...The investigation of reaction kinetics is the key to understanding the nature of reaction processes.However,monitoring fast photochemical reactions by mass spectrometry remains challenging.Herein,we developed an optical focusing inductive electrospray(OF-iESI)mass spectrometry platform for real-time and in-situ photoreaction monitoring.Coaxial irradiation from back of nanoelectrospray emitter with a taper section was utilized,so the emitter could act as optical lens to help achieving much larger optical power density at emitter tip compared to other sections,which allowed for in-situ reaction monitoring of photoreactions.Through theoretical calculations,the highest optical power density region volume was ca.45 nL.We also integrated a controller for the laser source(450 nm),enabling the modulation of pulse duration(>1 ms).This facilitates the study of photochemical reaction kinetics.The in-situ capability of this device was proved by capturing the short-lived photogenerated intermediates during the dehydrogenation of tetrahydroquinoline.This device was further used to investigate the kinetics of triplet energy transfer based Paternò-Büchi reaction.The reaction order has hitherto remained undetermined while the result of OF-iESI suggested it followed pseudo-second-order reaction kinetics.The short-lived donor-acceptor collision complex intermediate was also successfully identified by tandem mass spectrometry.展开更多
Designing highly active electrocatalysts for the hydrogen evolution reaction(HER)and oxygen evolution and reduction reactions(OER and ORR)is pivotal to renewable energy technology.Herein,based on density functional th...Designing highly active electrocatalysts for the hydrogen evolution reaction(HER)and oxygen evolution and reduction reactions(OER and ORR)is pivotal to renewable energy technology.Herein,based on density functional theory(DFT)calculations,we systematically investigate the catalytic activity of iron-nitrogen-carbon based covalent organic frameworks(COF)monolayers with axially coordinated ligands(denotes as Fe N_(4)-X@COF,X refers to axial ligand,X=-SCN,-I,-H,-SH,-NO_(2),-Br,-ClO,-Cl,-HCO_(3),-NO,-ClO_(2),-OH,-CN and-F).The calculated results demonstrate that all the catalysts possess good thermodynamic and electrochemical stabilities.The different ligands axially ligated to the Fe active center could induce changes in the charge of the Fe center,which further regulates the interaction strength between intermediates and catalysts that governs the catalytic activity.Importantly,FeN_(4)-SH@COF and Fe N_(4)-OH@COF are efficient bifunctional catalysts for HER and OER,FeN_(4)-OH@COF and FeN_(4)-I@COF are promising bifunctional catalysts for OER and ORR.These findings not only reveal promising bifunctional HER/OER and OER/ORR catalysts but also provide theoretical guidance for designing optimum ironnitrogen-carbon based catalysts.展开更多
Electrochemical carbon dioxide reduction reaction(CO_(2)RR)converts CO_(2) into valuable chemicals by consuming renewable electricity at mild conditions,making it a promising approach to achieving carbon neutrality.Ho...Electrochemical carbon dioxide reduction reaction(CO_(2)RR)converts CO_(2) into valuable chemicals by consuming renewable electricity at mild conditions,making it a promising approach to achieving carbon neutrality.However,the reaction of CO_(2) with hydroxide ions to form carbonates leads to low carbon utilization and energy efficiency in near-neutral or alkaline CO_(2)RR.The high concentration of protons in acidic media can effectively mitigate carbonate formation and deposition,thereby significantly minimizing carbon loss and energy consumption.Unfortunately,hydrogen evolution reaction(HER)is more kinetically favorable than CO_(2)RR in acidic media.Herein,we comprehensively overview recent progress in acidic CO_(2)RR and propose two strategies derived from the competing reaction pathways of HER and CO_(2)RR:one focuses on regulating the H+mass transport,while the other aims to modulate the intrinsic kinetic activity of CO_(2)RR.The two strategies are designed to compete for the limited active sites on the catalyst surface,inhibit side reactions,and enhance the activity and selectivity of CO_(2)RR.The representative approaches include modulating the interface electric field,constructing a local alkaline environment,and regulating competing adsorption sites.Finally,we also review the technical challenges and future perspectives of acidic CO_(2)RR coupled with membrane electrode assemblies(MEAs).展开更多
Three efficient methods for the synthesis of a series of Cu(Ⅱ) and Cu(Ⅰ) complexes based on imidazo[1,5-a]pyridine derivatives were developed.These methods include the following:(ⅰ)Cu(Ⅱ) salts were used as metal s...Three efficient methods for the synthesis of a series of Cu(Ⅱ) and Cu(Ⅰ) complexes based on imidazo[1,5-a]pyridine derivatives were developed.These methods include the following:(ⅰ)Cu(Ⅱ) salts were used as metal sources and N,N-dimethylformamide was employed as a solvent as well as a reductant to produce Cu(Ⅰ) complexes.(ⅱ) An iodide-containing compound was utilized as a ligand and iodide source to prepare complexes.An in situ metalligand reaction occurred and an iodide-bridged copper complex was generated.(ⅲ) A series of aldehydes were added to the reaction systems to induce in situ metal-ligand reactions between the aldehydes and the imidazo[1,5-a]pyridine derivatives,producing polydentate ligand scaffolds.Eight complexes were prepared and characterized.The catalytic activities of these complexes toward the ketalization of ketones by ethylene glycol were investigated.With the exception of complex4,the remaining seven complexes all showed high catalytic activity.The lower activity of 4 may be due to the larger radius of bridging iodide ions and the shorter Cu(Ⅰ)…Cu(Ⅰ) distance.CCDC:2357696,1·2CH_(2)Cl_(2);2357697,2;2018292,3;2092192,4;2092190,5;2155557,6;2406155,7;2406156,8·EtOH.展开更多
Continuous-flow upgrading of pentaerythritol synthesis technology via base-catalyzed aldol and Cannizzaro reactions of formaldehyde and acetaldehyde faces the challenge of effectively controlling the critical side rea...Continuous-flow upgrading of pentaerythritol synthesis technology via base-catalyzed aldol and Cannizzaro reactions of formaldehyde and acetaldehyde faces the challenge of effectively controlling the critical side reaction of hydroxymethyl acetaldehyde(HA)to the acrolein intermediate.Here,we first identified the forms of industrial formaldehyde as methane diol that easily converts to the alkaline formaldehyde under alkaline(NaOH)environment.The carbonyl group of alkaline formaldehyde induces deprotonation of acetaldehyde instead of the recognized base-hydroxyl group-induced deprotonation,and it needs to overcome only 18.31 kcal·mol^(-1)(1 kcal=4.186 kJ)energy barrier to form key intermediates of HA.The sodium solvation cage formed by NaOH hexa-coordinated formaldehyde effectively inhibits the alkalinity,thus contributing to a high energy barrier(46.21 kcal·mol^(-1))to unwanted acrolein formation.In addition,the solvation cage gradually opens to increase the alkalinity with the consumption of formaldehyde,thus facilitating the subsequent Cannizzaro reaction(to overcome 11.77 kcal·mol^(-1)).In comparison,strong alkalinity promotes the formation of acrolein(36.65 kcal·mol^(-1))to initiate the acetal side reaction,while weak alkalinity reduces the possibility of the Cannizzaro reaction(to overcome 20.44 kcal·mol^(-1)).This theoretically reveals the importance of the segmented feeding of weak and strong bases to successively control the aldol reaction and Cannizzaro reaction,and the combination of Na_(2)CO_(3) or HCOONa with NaOH improves the pentaerythritol yield by 7%to 13%compared to that of NaOH alone(70%yield)within 1 min at a throughput of 155.7 ml·min^(-1).展开更多
Unsaturated alcohols are a class of Biogenic volatile organic compounds(BVOCs)emitted in large quantities by plants when damaged or under adverse environmental conditions,and studies on their atmospheric degradation a...Unsaturated alcohols are a class of Biogenic volatile organic compounds(BVOCs)emitted in large quantities by plants when damaged or under adverse environmental conditions,and studies on their atmospheric degradation at night are still lacking.We used chamber experiments to study the gas-phase reactions of three unsaturated alcohols,E-2-penten-1-ol,Z-2-hexen-1-ol and Z-3-hepten-1-ol,with NO_(3)radicals(NO_(3)•)during the night.The rate constants of these reactions were(11.7±1.76)×10^(−13),(8.55±1.33)×10^(−13)and(6.08±0.47)×10^(−13)cm^(3)/(molecule·s)at 298K and 760 Torr,respectively.In contrast,the reaction rate of similar substances with ozone was about 10^(−18)cm^(3)/(molecule·s),which indicates that the reaction with NO_(3)•is themain oxidation pathway for unsaturated alcohols at night.Small molecule aldehydes and ketones were the main gas-phase organic products of the reaction of three aldehydes and ketones with NO_(3)•,and the total small molecule aldehydes and ketones yields can reach between 45%-60%.They mainly originate from the breakage of alkoxy radicals,and different breakage sites determine different product distributions.In addition,the SOA yields of the three unsaturated alcohols with NO_(3)•were 7.1%±1.0%,12.5%±1.9%and 30.0%±4.5%,respectively,whichweremuch higher than those of similarly structured substances with O_(3)or OH radicals(•OH).The results of high-resolution mass spectrometry shows that the main components of Secondary organic aerosol(SOA)of the three unsaturated alcohols are dimeric compounds containing several nitrate groups,which are formed through the polymerization of oxyalkyl radicals.展开更多
An in-depth understanding of the catalyst surface evolution is crucial for precise control of active sites,yet this aspect has often been overlooked.This study reveals the spontaneous anion regulation mechanism of Br-...An in-depth understanding of the catalyst surface evolution is crucial for precise control of active sites,yet this aspect has often been overlooked.This study reveals the spontaneous anion regulation mechanism of Br-doped CoP electrocatalysts in the alkaline hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).The introduction of Br modulates the electronic structure of the Co site,endowing Br-CoP with a more metallic character.In addition,P ion leaching promotes the in situ reconstruction of Br-CoOOH,which is the real active site for the OER reaction.Meanwhile,the HER situation is different.On the basis of P ion leaching,the leaching of Br ions promotes the formation of CoP-Co(OH)_(2) active species.In addition,Br doping enhances the adsorption of^(*)H,showing excellent H adsorption free energy,thereby greatly improving the HER activity.Simultaneously,it also enhances the adsorption of OOH^(*),effectively facilitating the occurrence of OER reactions.Br-CoP only needs 261 and 76 mV overpotential to drive the current density of 20 mA cm^(-2) and 10 mA^(-2),which can be maintained unchanged for 100 h.This study provides new insights into anion doping strategies and catalyst reconstruction mechanisms.展开更多
Hydrogen production from water electrolysis,in particular from proton exchange membrane water electrolyzers(PEMWE),is a key approach to realizing a carbon-free energy cycle.However,the high anodic potential and strong...Hydrogen production from water electrolysis,in particular from proton exchange membrane water electrolyzers(PEMWE),is a key approach to realizing a carbon-free energy cycle.However,the high anodic potential and strong acid in PEMWE systems pose a major challenge to the stability of electrocatalysts,and the development of efficient and corrosion-resistant catalysts is urgently needed.Currently,iridium(Ir)-based catalysts have gained great attention due to their promising activity and stability,while the extremely low reserves of Ir in the earth seriously hinder the commercialization of PEMWE.Therefore,a systematic understanding of the latest advances in Ir-based catalysts is necessary to guide their rational design to meet the industrial requirements.In this review,the general reaction mechanisms and advanced characterization techniques for mechanism recognition are first introduced.Afterwards,the systematic design strategies and performances of Ir-based catalysts,including metallic Ir,Ir oxides,and Ir-based perovskites,are summarized in detail.Finally,the conclusions,challenges,and prospects for Ir-based electrocatalysts are presented.展开更多
Lime is widely used to modify clayey soils to enhance their physical and chemical properties,and lime-treated soil has become a key material in transportation infrastructure.Chemical reactions were identified through ...Lime is widely used to modify clayey soils to enhance their physical and chemical properties,and lime-treated soil has become a key material in transportation infrastructure.Chemical reactions were identified through laboratory tests from field samples collected from the subgrade after 30 years of operation to understand its long-term performance evolution.Exchangeable calcium,carbonated calcium,and total calcium were quantified using ethylenediaminetetraacetic acid(EDTA)titration,gasometric analysis,and the strong acid extraction method,respectively.These measurements enabled the evaluation of calcium transformation during the pozzolanic reaction,providing a quantitative characterization of pozzolanic progression in the lime-treated clay matrix.Evolutions in pH,electrical conductivity,and salinity were also tracked.Mechanical performance was assessed through maximal shear modulus(Gmax)and unconfined compressive strength(UCS)tests.Then,the microstructure and mineral composition were analyzed via scanning electron microscopy(SEM)and X-ray diffraction(XRD).Furthermore,with an extended curing period,the pH,electrical conductivity,salinity,and exchangeable calcium content were found to decrease gradually.In contrast,the carbonation-related calcium content increased,and the clay mineral structures were significantly altered.The significant increase in Gmax and UCS is attributed to the formation of calcium-aluminate-silicate-hydrate(C-(A)-S-H)for pozzolanic and carbonation reactions where the clay mineral is involved.SEM reveals the curled edges of clay minerals and the formation of a 3D network.Additionally,XRD patterns further confirm the presence of increasing amounts of amorphous phases within the 2θrange of 15°–32°,indicating the progression of the pozzolanic reaction.展开更多
Bifunctional oxide-zeolite-based composites(OXZEO)have emerged as promising materials for the direct conversion of syngas to olefins.However,experimental screening and optimization of reaction parameters remain resour...Bifunctional oxide-zeolite-based composites(OXZEO)have emerged as promising materials for the direct conversion of syngas to olefins.However,experimental screening and optimization of reaction parameters remain resource-intensive.To address this challenge,we implemented a three-stage framework integrating machine learning,Bayesian optimization,and experimental validation,utilizing a carefully curated dataset from the literature.Our ensemble-tree model(R^(2)>0.87)identified Zn-Zr and Cu-Mg binary mixed oxides as the most effective OXZEO systems,with their light olefin space-time yields confirmed by physically mixing with HSAPO-34 through experimental validation.Density functional theory calculations further elucidated the activity trends between Zn-Zr and Cu-Mg mixed oxides.Among 16 catalyst and reaction condition descriptors,the oxide/zeolite ratio,reaction temperature,and pressure emerged as the most significant factors.This interpretable,data-driven framework offers a versatile approach that can be applied to other catalytic processes,providing a powerful tool for experiment design and optimization in catalysis.展开更多
The sluggish reaction kinetics of the oxygen evolution reaction(OER)and methanol oxidation reaction(MOR)remain obstacles to the commercial promotion of water splitting and direct methanol fuel cells.Considering the vi...The sluggish reaction kinetics of the oxygen evolution reaction(OER)and methanol oxidation reaction(MOR)remain obstacles to the commercial promotion of water splitting and direct methanol fuel cells.Considering the vital role of noble metals in electrocatalytic activity,this work focuses on the rational synthesis of Ni-noble metal composite nanocatalysts for overcoming the drawbacks of high cost and susceptible oxidized surfaces of noble metals.The inherent catalytic activity is improved by the altered electronic structure and effective active sites of the catalyst induced by the size effect of noble metal clusters.In particular,a series of Ni-noble metal nanocomposites are successfully synthesized by partially introducing noble metal into Ni with porous interfacial defects derived from Ni-Al layered double hydroxide(LDH).The Ni_(10)Pd_(1)nanocomposite exhibits high OER catalytic activity with an overpotential of 0.279 V at 10 m A/cm^(2),surpassing Ni_(10)Ag_(1)and Ni_(10)Au_(1)counterparts.Furthermore,the average diameter of Pd clusters gradually increases from 5.57 nm to 44.44 nm with the increased proportion of doped Pd,leading to the passivation of catalytic activity due to the exacerbated surface oxidation of Pd in the form of Pd^(2+).After optimization,Ni_(10)Pd_(1)delivers significantly enhanced OER and MOR electroactivities and long-term stability compared to that of Ni_(2)Pd_(1),Ni_(1)Pd_(1)and Ni_(1)Pd_(2),which is conducive to the effective utilization of Pd and alleviation of surface oxidation.展开更多
Efficient catalysis of the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is essential for the rechargeable zinc-air batteries(R-ZABs).However,challenges remain due to the scarcity of effective bifunc...Efficient catalysis of the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is essential for the rechargeable zinc-air batteries(R-ZABs).However,challenges remain due to the scarcity of effective bifunctional electrocatalysts and limited understanding of the structure-activity relationships.Pyrrole-type single-atom catalysts(SACs)with unique electronic structures have emerged as promising electrocatalysts.In this work,we combine density functional theory(DFT)calculations and experimental studies to systematically explore the structure-activity relationships and potential of pyrrole-type transition metal-N_(3)(TM-po-N_(3))as bifunctional catalysts.DFT calculations reveal that differences in the dependence of ORR and OER activities on the free energy of adsorption of reaction intermediates significantly affect the TM-po-N_(3)bifunctional activity and identify magnetic Cu-po-N_(3)as the best candidate.The bifunctional activity of Cu-po-N_(3)originates from interactions between spin-polarized out-of-plane Cu_3d and O_2s+2p orbitals.Theoretical predictions are validated experimentally,showing that the synthesized Cu-SAC/NC exhibits excellent bifunctional performance with a small potential gap of 0.666 V.Additionally,the assembled R-ZABs display a high-power density of 170 mW cm^(-2)and long-term stability,with the charge-discharge voltage gap increasing by only 0.01 V over 240 h.This work provides new insights into the design of efficient bifunctional catalysts.展开更多
CO_(2)injection into geological formations has been proven to be an effective approach for carbon storage.When dissolved in formation water,CO_(2)forms carbonic acid that induces mineral dissolution at pore surfaces u...CO_(2)injection into geological formations has been proven to be an effective approach for carbon storage.When dissolved in formation water,CO_(2)forms carbonic acid that induces mineral dissolution at pore surfaces under acidic conditions.Comprehensive understanding of geochemical interaction between carbonic acid and reservoir rocks is crucial for assessing environmental impact on geological formations.This study focuses on a tight oil sandstone reservoir.After characterizing basic petrophysical properties and mineral composition of rock samples,a series of carbonic acid corrosion experiments with both core and corresponding pure mineral samples were carried out,respectively.Dissolution solutions collected during the experiments were analyzed to examine the variations of ion concentrations in both core and pure mineral solutions.The carbonic acid-pure mineral corrosion kinetics were investigated.The correlations between carbonic acid with core and pure mineral corrosion scenarios were established from the sample mass,reaction rate,and ion concentration.The results show that after corrosion,the mass of calcite and dolomite in the rock sample decreased by 66.7%and 27.3%,respectively.When the corrosion was stabilized,the concentrations of Ca^(2+)and Mg^(2+)in the core solution were 72.9 and 74.4 mg/L.respectively,which was 40.5-41.3 times higher than that of Na+.The reaction kinetics analysis of carbonic acid-rock revealed a two-stage reaction in the pure mineral corrosion process,rapid reaction stage,and slow reaction stage,with different reaction rate constants and reaction orders for each ion.With the correlation between carbonic acid reaction with core and pure minerals,an effective and rapid evaluation method with pure minerals for the carbonic water-rock reaction is established,which costs a shorter time and is easier to investigate.This study provides a simple and faster method to evaluate the carbonic acid corrosion reaction during geological carbon storage.展开更多
CoFe bimetallic hydroxides(CoFe BMHs)find wide applications as excellent catalysts in the field of water splitting.However,no study has systematically investigated the influence of the morphologies of CoFe BMHs on cat...CoFe bimetallic hydroxides(CoFe BMHs)find wide applications as excellent catalysts in the field of water splitting.However,no study has systematically investigated the influence of the morphologies of CoFe BMHs on catalyst performance.In this study,CoFe BMH nanoflowers(CoFe BMH NFs),CoFe BMH nanosheets(CoFe BMH NSHs),CoFe BMH nanorods(CoFe BMH NRs),and CoFe BMH nanospheres(CoFe BMH NSPs)were prepared on nickel foam via a hydrothermal method.CoFe BMH NSHs exhibited the most beneficial catalytic activity.At a current density of 100 mA·cm^(-2),its overpotential for oxygen evolution reaction(OER)was 282 mV,and the overall water splitting voltage was 2.05 V.The double-layer charging capacitance(Cdl)value of CoFe BMH NSHs was the largest in CoFe BMHs,which proves that CoFe BMH NSHs have the largest active area.Furthermore,the active site in the OER process was metal oxyhydroxide(MOOH)through in situ Raman characterization,and the generation of the active substance was an irreversible process.This work provides important insights into the design of catalyst morphologies and offers valuable guidelines for the enhancement of the performance of other catalysts.展开更多
Hydrogen peroxide(H_(2)O_(2))electrosynthesis via two-electron oxygen reduction reaction(2e-ORR)is a promising alternative for the energy-intensive anthraquinone process.However,the instability of the catalytic metal ...Hydrogen peroxide(H_(2)O_(2))electrosynthesis via two-electron oxygen reduction reaction(2e-ORR)is a promising alternative for the energy-intensive anthraquinone process.However,the instability of the catalytic metal sites in the state-of-the-art metal single-atom catalysts(M-SACs)hinders their further industrial applications,and the high potential and valueless oxygen product of the conventional anodic oxygen evolution reaction(OER)further limit the economic efficiency of this technology.To address this,a dynamically local structure reconstruction strategy is proposed to in situ transfer the active sites from unstable metal sites to the stable surrounding carbon sites for efficient and durable 2e^(-)ORR electrocatalysis.For the as-designed Mn-N_(3)O-C catalyst,by reconstructing Mn sites into Mn(^(*)OH),the Mn sites were passivated and carbon sites adjacent to the O atom were verified to be the actual active sites by in situ characterization and theoretical calculation.Consequently,Mn-N_(3)O-C exhibited>80%Faradaic efficiency and superior long-term durability over 100 h for H_(2)O_(2)electrosynthesis at~120 mA cm^(-2).In addition,coupling anodic ethylene glycol oxidation reaction(EGOR)further improves the efficiency and economic viability of the H_(2)O_(2)electrosynthesis system.This two-pronged strategy thus opens up a new opportunity for the development of stable H_(2)O_(2)electrosynthesis with low energy consumption and superior economic performance.展开更多
Development of high-efficiency bifunctional oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)electrocatalysts is vital for the widespread application of zinc-air batteries(ZABs).However,it still remains...Development of high-efficiency bifunctional oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)electrocatalysts is vital for the widespread application of zinc-air batteries(ZABs).However,it still remains a great challenge to avoid the inhomogeneous distribution and aggregation of metal single-atomic active centers in the construction of bifunctional electrocatalysts with atomically dispersed multimetallic sites because of the common calcination method.Herein,we report a novel catalyst with phthalocyanine-assembled Fe-Co-Ni single-atomic triple sites dispersed on sulfur-doped graphene using a simple ultrasonic procedure without calcination,and X-ray absorption fine structure(XAFS),aberration-corrected scanning transmission electron microscopy(AC-STEM),and other detailed characterizations are performed to demonstrate the successful synthesis.The novel catalyst shows extraordinary bifunctional ORR/OER activities with a fairly low potential difference(ΔE=0.621 V)between the OER overpotential(Ej10=315 mV at 10 m A cm^(-2))and the ORR half-wave potential(Ehalf-wave=0.924 V).Moreover,the above catalyst shows excellent ZAB performance,with an outstanding specific capacity(786 mAh g^(-1)),noteworthy maximum power density(139 mW cm^(-2)),and extraordinary rechargeability(discharged and charged at 5 mA cm^(-2) for more than 1000 h).Theoretical calculations reveal the vital importance of the preferable synergetic coupling effect between adjacent active sites in the Fe-Co-Ni trimetallic single-atomic sites during the ORR/OER processes.This study provides a new avenue for the investigation of bifunctional electrocatalysts with atomically dispersed trimetallic sites,which is intended for enhancing the ORR/OER performance in ZABs.展开更多
Driving of the nuclear fusion reaction p+^(11)B3α+8.7 MeV under laboratory conditions by interaction between high-power laser pulses and matter has become a popular field of research,owing to its numerous potential a...Driving of the nuclear fusion reaction p+^(11)B3α+8.7 MeV under laboratory conditions by interaction between high-power laser pulses and matter has become a popular field of research,owing to its numerous potential applications:as an alternative to deuterium-tritium for fusion energy production,astrophysics studies,and alpha-particle generation for medical treatment.One possible scheme for laser-driven p-^(11)B reactions is to direct a beam of laser-accelerated protons onto a boron(B)sample(the so-called“pitcher-catcher”scheme).This technique has been successfully implemented on large high-energy lasers,yielding hundreds of joules per shot at low repetition.We present here a complementary approach,exploiting the high repetition rate of the VEGA III petawatt laser at CLPU(Spain),aiming at accumulating results from many interactions at much lower energy,to provide better control of the parameters and the statistics of the measurements.Despite a moderate energy per pulse,our experiment allowed exploration of the laser-driven fusion process with tens(up to hundreds)of laser shots.The experiment provided a clear signature of the reactions involved and of the fusion products,accumulated over many shots,leading to an improved optimization of the diagnostics for experimental campaigns of this type.In this paper,we discuss the effectiveness of laser-driven p-11B fusion in the pitcher-catcher scheme,at a high repetition rate,addressing the challenges of this experimental scheme and highlighting its critical aspects.Our proposed methodology allows evaluation of the performance of this scheme for laser-driven alpha particle production and can be adapted to high-repetition-rate laser facilities with higher energy and intensity.展开更多
Hydrogen evolution reaction(HER)is unavoidable in many electrochemical synthesis systems,such as CO_(2)reduction,N2reduction,and H_(2)O_(2)synthesis.It makes those electrochemical reactions with multiple electron-prot...Hydrogen evolution reaction(HER)is unavoidable in many electrochemical synthesis systems,such as CO_(2)reduction,N2reduction,and H_(2)O_(2)synthesis.It makes those electrochemical reactions with multiple electron-proton transfers more complex when determining kinetics and mass transfer information.Understanding how HER competes with other electrochemical reduction reactions is crucial for both fundamental studies and system performance improvements.In this study,we employed the oxygen reduction reaction(ORR)as a model reaction to investigate HER competition on a polycrystalline-Au surface,using a rotating ring and disk electrode.It’s proved that water molecules serve as the proton source for ORR in alkaline,neutral,and even acidic electrolytes,and a 4-electron process can be achieved when the overpotential is sufficiently high.The competition from H⁺reduction becomes noticeable at the H⁺concentration higher than 2 mmol L^(–1)and intensi-fies as the H^(+)concentration increases.Based on the electrochemical results,we obtained an equivalent circuit diagram for the ORR system with competition from the H+reduction reaction,showing that these reactions occur in parallel and compete with each other.Electrochemical impedance spectroscopy measurements further confirm this argument.Additionally,we discover that the contribution of H+mass transfer to the total H^(+)reduction current is significant and comparable to the kinetic current.We believe this work will deepen our understanding of HER and its competition in electrochemical reduction systems.展开更多
Pt-based materials are the benchmarked catalysts in the cathodic hydrogen evolution reaction(HER)of water splitting;the prohibitive cost and scarcity of Pt immensely impede the commercialization of hydrogen energy.Ru ...Pt-based materials are the benchmarked catalysts in the cathodic hydrogen evolution reaction(HER)of water splitting;the prohibitive cost and scarcity of Pt immensely impede the commercialization of hydrogen energy.Ru has aroused significant concern because of its Pt-like activity and much lower price.However,it’s still a top priority to minimize the Ru loading and pursue the most superior cost performance.展开更多
Ag/Al_(2)O_(3) powders are highly effective catalytic materials utilized in the epoxidation of ethylene to produce ethylene oxide.One of the critical challenges in this catalytic process is the stability of nano-sized...Ag/Al_(2)O_(3) powders are highly effective catalytic materials utilized in the epoxidation of ethylene to produce ethylene oxide.One of the critical challenges in this catalytic process is the stability of nano-sized Ag particles,especially during high-temperature catalysis.However,this issue can be effectively addressed through in-situ reaction synthesis.To gain a deeper understanding of the underlying mechanisms,the phase transformation process and the thermodynamic mechanism of the oxidation reaction in the Ag/Al_(2)O_(3) system have been investigated using firstprinciples thermodynamic calculations in conjunction with traditional thermodynamic data.These calculations,whose accuracy has been verified,provide valuable insights into the behavior of Ag and Al under different conditions.The results indicate that,during AgAl solid-solution oxidation,Ag-containing Al preferentially forms the stable intermediate phase Ag2Al instead of undergoing direct oxidation;this pathway becomes thermodynamically more favorable at higher Ag concentrations.With increasing temperature,Ag2Al is further oxidized to yield Ag and Al_(2)O_(3).It is also found that above 237℃,Ag2O and AgAlO2 become unstable.The overall reaction pathway is solid solution→Ag2Al→Ag+Al_(2)O_(3).This comprehensive study provides a robust theoretical calculation basis for the development and optimization of in-situ reaction-synthesized Ag/Al_(2)O_(3) powder composite materials,which have significant potential for practical applications in catalysis.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.22104112 and 22374110)the Fundamental Research Funds for the Central Universities。
文摘The investigation of reaction kinetics is the key to understanding the nature of reaction processes.However,monitoring fast photochemical reactions by mass spectrometry remains challenging.Herein,we developed an optical focusing inductive electrospray(OF-iESI)mass spectrometry platform for real-time and in-situ photoreaction monitoring.Coaxial irradiation from back of nanoelectrospray emitter with a taper section was utilized,so the emitter could act as optical lens to help achieving much larger optical power density at emitter tip compared to other sections,which allowed for in-situ reaction monitoring of photoreactions.Through theoretical calculations,the highest optical power density region volume was ca.45 nL.We also integrated a controller for the laser source(450 nm),enabling the modulation of pulse duration(>1 ms).This facilitates the study of photochemical reaction kinetics.The in-situ capability of this device was proved by capturing the short-lived photogenerated intermediates during the dehydrogenation of tetrahydroquinoline.This device was further used to investigate the kinetics of triplet energy transfer based Paternò-Büchi reaction.The reaction order has hitherto remained undetermined while the result of OF-iESI suggested it followed pseudo-second-order reaction kinetics.The short-lived donor-acceptor collision complex intermediate was also successfully identified by tandem mass spectrometry.
基金supported by the National Natural Science Foundation of China(Nos.22102167 and U21A20317)。
文摘Designing highly active electrocatalysts for the hydrogen evolution reaction(HER)and oxygen evolution and reduction reactions(OER and ORR)is pivotal to renewable energy technology.Herein,based on density functional theory(DFT)calculations,we systematically investigate the catalytic activity of iron-nitrogen-carbon based covalent organic frameworks(COF)monolayers with axially coordinated ligands(denotes as Fe N_(4)-X@COF,X refers to axial ligand,X=-SCN,-I,-H,-SH,-NO_(2),-Br,-ClO,-Cl,-HCO_(3),-NO,-ClO_(2),-OH,-CN and-F).The calculated results demonstrate that all the catalysts possess good thermodynamic and electrochemical stabilities.The different ligands axially ligated to the Fe active center could induce changes in the charge of the Fe center,which further regulates the interaction strength between intermediates and catalysts that governs the catalytic activity.Importantly,FeN_(4)-SH@COF and Fe N_(4)-OH@COF are efficient bifunctional catalysts for HER and OER,FeN_(4)-OH@COF and FeN_(4)-I@COF are promising bifunctional catalysts for OER and ORR.These findings not only reveal promising bifunctional HER/OER and OER/ORR catalysts but also provide theoretical guidance for designing optimum ironnitrogen-carbon based catalysts.
基金supported by the National Natural Science Foundation of China(52301259 and 22208019)the Research Fund Program for Young Scholars of Beijing Institute of Technology。
文摘Electrochemical carbon dioxide reduction reaction(CO_(2)RR)converts CO_(2) into valuable chemicals by consuming renewable electricity at mild conditions,making it a promising approach to achieving carbon neutrality.However,the reaction of CO_(2) with hydroxide ions to form carbonates leads to low carbon utilization and energy efficiency in near-neutral or alkaline CO_(2)RR.The high concentration of protons in acidic media can effectively mitigate carbonate formation and deposition,thereby significantly minimizing carbon loss and energy consumption.Unfortunately,hydrogen evolution reaction(HER)is more kinetically favorable than CO_(2)RR in acidic media.Herein,we comprehensively overview recent progress in acidic CO_(2)RR and propose two strategies derived from the competing reaction pathways of HER and CO_(2)RR:one focuses on regulating the H+mass transport,while the other aims to modulate the intrinsic kinetic activity of CO_(2)RR.The two strategies are designed to compete for the limited active sites on the catalyst surface,inhibit side reactions,and enhance the activity and selectivity of CO_(2)RR.The representative approaches include modulating the interface electric field,constructing a local alkaline environment,and regulating competing adsorption sites.Finally,we also review the technical challenges and future perspectives of acidic CO_(2)RR coupled with membrane electrode assemblies(MEAs).
文摘Three efficient methods for the synthesis of a series of Cu(Ⅱ) and Cu(Ⅰ) complexes based on imidazo[1,5-a]pyridine derivatives were developed.These methods include the following:(ⅰ)Cu(Ⅱ) salts were used as metal sources and N,N-dimethylformamide was employed as a solvent as well as a reductant to produce Cu(Ⅰ) complexes.(ⅱ) An iodide-containing compound was utilized as a ligand and iodide source to prepare complexes.An in situ metalligand reaction occurred and an iodide-bridged copper complex was generated.(ⅲ) A series of aldehydes were added to the reaction systems to induce in situ metal-ligand reactions between the aldehydes and the imidazo[1,5-a]pyridine derivatives,producing polydentate ligand scaffolds.Eight complexes were prepared and characterized.The catalytic activities of these complexes toward the ketalization of ketones by ethylene glycol were investigated.With the exception of complex4,the remaining seven complexes all showed high catalytic activity.The lower activity of 4 may be due to the larger radius of bridging iodide ions and the shorter Cu(Ⅰ)…Cu(Ⅰ) distance.CCDC:2357696,1·2CH_(2)Cl_(2);2357697,2;2018292,3;2092192,4;2092190,5;2155557,6;2406155,7;2406156,8·EtOH.
基金funded by the National Natural Science Foundation of China(22478632)Key Scientific and Technological Project of Henan Province(242102321032).
文摘Continuous-flow upgrading of pentaerythritol synthesis technology via base-catalyzed aldol and Cannizzaro reactions of formaldehyde and acetaldehyde faces the challenge of effectively controlling the critical side reaction of hydroxymethyl acetaldehyde(HA)to the acrolein intermediate.Here,we first identified the forms of industrial formaldehyde as methane diol that easily converts to the alkaline formaldehyde under alkaline(NaOH)environment.The carbonyl group of alkaline formaldehyde induces deprotonation of acetaldehyde instead of the recognized base-hydroxyl group-induced deprotonation,and it needs to overcome only 18.31 kcal·mol^(-1)(1 kcal=4.186 kJ)energy barrier to form key intermediates of HA.The sodium solvation cage formed by NaOH hexa-coordinated formaldehyde effectively inhibits the alkalinity,thus contributing to a high energy barrier(46.21 kcal·mol^(-1))to unwanted acrolein formation.In addition,the solvation cage gradually opens to increase the alkalinity with the consumption of formaldehyde,thus facilitating the subsequent Cannizzaro reaction(to overcome 11.77 kcal·mol^(-1)).In comparison,strong alkalinity promotes the formation of acrolein(36.65 kcal·mol^(-1))to initiate the acetal side reaction,while weak alkalinity reduces the possibility of the Cannizzaro reaction(to overcome 20.44 kcal·mol^(-1)).This theoretically reveals the importance of the segmented feeding of weak and strong bases to successively control the aldol reaction and Cannizzaro reaction,and the combination of Na_(2)CO_(3) or HCOONa with NaOH improves the pentaerythritol yield by 7%to 13%compared to that of NaOH alone(70%yield)within 1 min at a throughput of 155.7 ml·min^(-1).
基金supported by the National Key Research and Development Program of China(No.2020YFA0607800)the National Natural Science Foundation of China(Nos.42022039 and 42130606)Beijing National Laboratory for Molecular Sciences(No.BNLMS-CXXM-202011),the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.Y2021013).
文摘Unsaturated alcohols are a class of Biogenic volatile organic compounds(BVOCs)emitted in large quantities by plants when damaged or under adverse environmental conditions,and studies on their atmospheric degradation at night are still lacking.We used chamber experiments to study the gas-phase reactions of three unsaturated alcohols,E-2-penten-1-ol,Z-2-hexen-1-ol and Z-3-hepten-1-ol,with NO_(3)radicals(NO_(3)•)during the night.The rate constants of these reactions were(11.7±1.76)×10^(−13),(8.55±1.33)×10^(−13)and(6.08±0.47)×10^(−13)cm^(3)/(molecule·s)at 298K and 760 Torr,respectively.In contrast,the reaction rate of similar substances with ozone was about 10^(−18)cm^(3)/(molecule·s),which indicates that the reaction with NO_(3)•is themain oxidation pathway for unsaturated alcohols at night.Small molecule aldehydes and ketones were the main gas-phase organic products of the reaction of three aldehydes and ketones with NO_(3)•,and the total small molecule aldehydes and ketones yields can reach between 45%-60%.They mainly originate from the breakage of alkoxy radicals,and different breakage sites determine different product distributions.In addition,the SOA yields of the three unsaturated alcohols with NO_(3)•were 7.1%±1.0%,12.5%±1.9%and 30.0%±4.5%,respectively,whichweremuch higher than those of similarly structured substances with O_(3)or OH radicals(•OH).The results of high-resolution mass spectrometry shows that the main components of Secondary organic aerosol(SOA)of the three unsaturated alcohols are dimeric compounds containing several nitrate groups,which are formed through the polymerization of oxyalkyl radicals.
基金supported by the National Natural Science Foundation of China(62404063)the Natural Science Foundation of Heilongjiang Province(YQ2022B008,LH2023A011)+1 种基金the Basic research support plan project for outstanding young teachers in undergraduate universities of Heilongjiang Province(YQJH2023160)the Basic scientific research business expense project of Heilongjiang Provincial Department of Education(2022-KYYWF-0170).
文摘An in-depth understanding of the catalyst surface evolution is crucial for precise control of active sites,yet this aspect has often been overlooked.This study reveals the spontaneous anion regulation mechanism of Br-doped CoP electrocatalysts in the alkaline hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).The introduction of Br modulates the electronic structure of the Co site,endowing Br-CoP with a more metallic character.In addition,P ion leaching promotes the in situ reconstruction of Br-CoOOH,which is the real active site for the OER reaction.Meanwhile,the HER situation is different.On the basis of P ion leaching,the leaching of Br ions promotes the formation of CoP-Co(OH)_(2) active species.In addition,Br doping enhances the adsorption of^(*)H,showing excellent H adsorption free energy,thereby greatly improving the HER activity.Simultaneously,it also enhances the adsorption of OOH^(*),effectively facilitating the occurrence of OER reactions.Br-CoP only needs 261 and 76 mV overpotential to drive the current density of 20 mA cm^(-2) and 10 mA^(-2),which can be maintained unchanged for 100 h.This study provides new insights into anion doping strategies and catalyst reconstruction mechanisms.
基金supported by the National Natural Science Foundation of China(22202053,22109035,52362031,and 52274297)the start-up Research Foundation of Hainan University(KYQD(ZR)-20008,20083,20084,23068,and 23169)+4 种基金the Hainan Province Science and Technology Special Fund(ZDYF2024SHFZ074)the Collaborative Innovation Center of Marine Science and Technology,Hainan University(XTCX2022HYC04)the specific research fund of The Innovation Platform for Academicians of Hainan Province(YSPTZX202315)the Research Fund Program of Guangdong Provincial Key Laboratory of Fuel Cell Technology(FC202307)the Open Fund Project of Key Laboratory of Electrochemical Energy Storage and Energy Conversion in Hainan Province of China(KFKT2023002)。
文摘Hydrogen production from water electrolysis,in particular from proton exchange membrane water electrolyzers(PEMWE),is a key approach to realizing a carbon-free energy cycle.However,the high anodic potential and strong acid in PEMWE systems pose a major challenge to the stability of electrocatalysts,and the development of efficient and corrosion-resistant catalysts is urgently needed.Currently,iridium(Ir)-based catalysts have gained great attention due to their promising activity and stability,while the extremely low reserves of Ir in the earth seriously hinder the commercialization of PEMWE.Therefore,a systematic understanding of the latest advances in Ir-based catalysts is necessary to guide their rational design to meet the industrial requirements.In this review,the general reaction mechanisms and advanced characterization techniques for mechanism recognition are first introduced.Afterwards,the systematic design strategies and performances of Ir-based catalysts,including metallic Ir,Ir oxides,and Ir-based perovskites,are summarized in detail.Finally,the conclusions,challenges,and prospects for Ir-based electrocatalysts are presented.
基金supported by the National Natural Science Foundation of China(Grant No.42302311)the ARC Discovery Project Program(Grant Nos.DP210100437 and DP230100126).
文摘Lime is widely used to modify clayey soils to enhance their physical and chemical properties,and lime-treated soil has become a key material in transportation infrastructure.Chemical reactions were identified through laboratory tests from field samples collected from the subgrade after 30 years of operation to understand its long-term performance evolution.Exchangeable calcium,carbonated calcium,and total calcium were quantified using ethylenediaminetetraacetic acid(EDTA)titration,gasometric analysis,and the strong acid extraction method,respectively.These measurements enabled the evaluation of calcium transformation during the pozzolanic reaction,providing a quantitative characterization of pozzolanic progression in the lime-treated clay matrix.Evolutions in pH,electrical conductivity,and salinity were also tracked.Mechanical performance was assessed through maximal shear modulus(Gmax)and unconfined compressive strength(UCS)tests.Then,the microstructure and mineral composition were analyzed via scanning electron microscopy(SEM)and X-ray diffraction(XRD).Furthermore,with an extended curing period,the pH,electrical conductivity,salinity,and exchangeable calcium content were found to decrease gradually.In contrast,the carbonation-related calcium content increased,and the clay mineral structures were significantly altered.The significant increase in Gmax and UCS is attributed to the formation of calcium-aluminate-silicate-hydrate(C-(A)-S-H)for pozzolanic and carbonation reactions where the clay mineral is involved.SEM reveals the curled edges of clay minerals and the formation of a 3D network.Additionally,XRD patterns further confirm the presence of increasing amounts of amorphous phases within the 2θrange of 15°–32°,indicating the progression of the pozzolanic reaction.
基金funded by the KRICT Project (KK2512-10) of the Korea Research Institute of Chemical Technology and the Ministry of Trade, Industry and Energy (MOTIE)the Korea Institute for Advancement of Technology (KIAT) through the Virtual Engineering Platform Program (P0022334)+1 种基金supported by the Carbon Neutral Industrial Strategic Technology Development Program (RS-202300261088) funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea)Further support was provided by research fund of Chungnam National University。
文摘Bifunctional oxide-zeolite-based composites(OXZEO)have emerged as promising materials for the direct conversion of syngas to olefins.However,experimental screening and optimization of reaction parameters remain resource-intensive.To address this challenge,we implemented a three-stage framework integrating machine learning,Bayesian optimization,and experimental validation,utilizing a carefully curated dataset from the literature.Our ensemble-tree model(R^(2)>0.87)identified Zn-Zr and Cu-Mg binary mixed oxides as the most effective OXZEO systems,with their light olefin space-time yields confirmed by physically mixing with HSAPO-34 through experimental validation.Density functional theory calculations further elucidated the activity trends between Zn-Zr and Cu-Mg mixed oxides.Among 16 catalyst and reaction condition descriptors,the oxide/zeolite ratio,reaction temperature,and pressure emerged as the most significant factors.This interpretable,data-driven framework offers a versatile approach that can be applied to other catalytic processes,providing a powerful tool for experiment design and optimization in catalysis.
基金support by the National Natural Science Foundation of China(Nos.U20A20123,51874357,22379166)Natural Science Foundation for Distinguished Young Scholars of Hunan Province(No.2022JJ10089)。
文摘The sluggish reaction kinetics of the oxygen evolution reaction(OER)and methanol oxidation reaction(MOR)remain obstacles to the commercial promotion of water splitting and direct methanol fuel cells.Considering the vital role of noble metals in electrocatalytic activity,this work focuses on the rational synthesis of Ni-noble metal composite nanocatalysts for overcoming the drawbacks of high cost and susceptible oxidized surfaces of noble metals.The inherent catalytic activity is improved by the altered electronic structure and effective active sites of the catalyst induced by the size effect of noble metal clusters.In particular,a series of Ni-noble metal nanocomposites are successfully synthesized by partially introducing noble metal into Ni with porous interfacial defects derived from Ni-Al layered double hydroxide(LDH).The Ni_(10)Pd_(1)nanocomposite exhibits high OER catalytic activity with an overpotential of 0.279 V at 10 m A/cm^(2),surpassing Ni_(10)Ag_(1)and Ni_(10)Au_(1)counterparts.Furthermore,the average diameter of Pd clusters gradually increases from 5.57 nm to 44.44 nm with the increased proportion of doped Pd,leading to the passivation of catalytic activity due to the exacerbated surface oxidation of Pd in the form of Pd^(2+).After optimization,Ni_(10)Pd_(1)delivers significantly enhanced OER and MOR electroactivities and long-term stability compared to that of Ni_(2)Pd_(1),Ni_(1)Pd_(1)and Ni_(1)Pd_(2),which is conducive to the effective utilization of Pd and alleviation of surface oxidation.
基金supported by the Hainan Province Science and Technology Special Fund(ZDYF2020037)the National Natural Science Foundation of China(22109035,52164028,52274297,22462006)+3 种基金the Postdoctoral Science Foundation of Hainan Province(RZ2100007123)the Basic and Applied Basic Research Foundation of Guangdong Province(2019A1515110558)the Start-up Research Foundation of Hainan University(KYQD(ZR)-20008,20083,20084,21125)Hainan University(XTCX2022HYC05)。
文摘Efficient catalysis of the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is essential for the rechargeable zinc-air batteries(R-ZABs).However,challenges remain due to the scarcity of effective bifunctional electrocatalysts and limited understanding of the structure-activity relationships.Pyrrole-type single-atom catalysts(SACs)with unique electronic structures have emerged as promising electrocatalysts.In this work,we combine density functional theory(DFT)calculations and experimental studies to systematically explore the structure-activity relationships and potential of pyrrole-type transition metal-N_(3)(TM-po-N_(3))as bifunctional catalysts.DFT calculations reveal that differences in the dependence of ORR and OER activities on the free energy of adsorption of reaction intermediates significantly affect the TM-po-N_(3)bifunctional activity and identify magnetic Cu-po-N_(3)as the best candidate.The bifunctional activity of Cu-po-N_(3)originates from interactions between spin-polarized out-of-plane Cu_3d and O_2s+2p orbitals.Theoretical predictions are validated experimentally,showing that the synthesized Cu-SAC/NC exhibits excellent bifunctional performance with a small potential gap of 0.666 V.Additionally,the assembled R-ZABs display a high-power density of 170 mW cm^(-2)and long-term stability,with the charge-discharge voltage gap increasing by only 0.01 V over 240 h.This work provides new insights into the design of efficient bifunctional catalysts.
基金the National Natural Science Foundation of China(52474073,52288101,52120105007,51804327)Shandong Provincial Natural Science Foundation(ZR2023ME016)Climb Taishan Scholar Program in Shandong Province(tspd20230605).
文摘CO_(2)injection into geological formations has been proven to be an effective approach for carbon storage.When dissolved in formation water,CO_(2)forms carbonic acid that induces mineral dissolution at pore surfaces under acidic conditions.Comprehensive understanding of geochemical interaction between carbonic acid and reservoir rocks is crucial for assessing environmental impact on geological formations.This study focuses on a tight oil sandstone reservoir.After characterizing basic petrophysical properties and mineral composition of rock samples,a series of carbonic acid corrosion experiments with both core and corresponding pure mineral samples were carried out,respectively.Dissolution solutions collected during the experiments were analyzed to examine the variations of ion concentrations in both core and pure mineral solutions.The carbonic acid-pure mineral corrosion kinetics were investigated.The correlations between carbonic acid with core and pure mineral corrosion scenarios were established from the sample mass,reaction rate,and ion concentration.The results show that after corrosion,the mass of calcite and dolomite in the rock sample decreased by 66.7%and 27.3%,respectively.When the corrosion was stabilized,the concentrations of Ca^(2+)and Mg^(2+)in the core solution were 72.9 and 74.4 mg/L.respectively,which was 40.5-41.3 times higher than that of Na+.The reaction kinetics analysis of carbonic acid-rock revealed a two-stage reaction in the pure mineral corrosion process,rapid reaction stage,and slow reaction stage,with different reaction rate constants and reaction orders for each ion.With the correlation between carbonic acid reaction with core and pure minerals,an effective and rapid evaluation method with pure minerals for the carbonic water-rock reaction is established,which costs a shorter time and is easier to investigate.This study provides a simple and faster method to evaluate the carbonic acid corrosion reaction during geological carbon storage.
基金supported by the National Science Fund for Distinguished Young Scholars(No.52025041)the National Natural Science Foundation of China(Nos.52474319,52250091,U2341267,and 52450003)+1 种基金the Fundamental Research Funds for the Central Universities(No.FRF-TP-20-02C2)supported by the Interdisciplinary Research Project for Young Teachers of USTB,China(Fundamental Research Funds for the Central Universities)(No.FRF-IDRY-GD23-003).
文摘CoFe bimetallic hydroxides(CoFe BMHs)find wide applications as excellent catalysts in the field of water splitting.However,no study has systematically investigated the influence of the morphologies of CoFe BMHs on catalyst performance.In this study,CoFe BMH nanoflowers(CoFe BMH NFs),CoFe BMH nanosheets(CoFe BMH NSHs),CoFe BMH nanorods(CoFe BMH NRs),and CoFe BMH nanospheres(CoFe BMH NSPs)were prepared on nickel foam via a hydrothermal method.CoFe BMH NSHs exhibited the most beneficial catalytic activity.At a current density of 100 mA·cm^(-2),its overpotential for oxygen evolution reaction(OER)was 282 mV,and the overall water splitting voltage was 2.05 V.The double-layer charging capacitance(Cdl)value of CoFe BMH NSHs was the largest in CoFe BMHs,which proves that CoFe BMH NSHs have the largest active area.Furthermore,the active site in the OER process was metal oxyhydroxide(MOOH)through in situ Raman characterization,and the generation of the active substance was an irreversible process.This work provides important insights into the design of catalyst morphologies and offers valuable guidelines for the enhancement of the performance of other catalysts.
基金supported by the National Natural Science Foundation of China(22379111 and 22179093)。
文摘Hydrogen peroxide(H_(2)O_(2))electrosynthesis via two-electron oxygen reduction reaction(2e-ORR)is a promising alternative for the energy-intensive anthraquinone process.However,the instability of the catalytic metal sites in the state-of-the-art metal single-atom catalysts(M-SACs)hinders their further industrial applications,and the high potential and valueless oxygen product of the conventional anodic oxygen evolution reaction(OER)further limit the economic efficiency of this technology.To address this,a dynamically local structure reconstruction strategy is proposed to in situ transfer the active sites from unstable metal sites to the stable surrounding carbon sites for efficient and durable 2e^(-)ORR electrocatalysis.For the as-designed Mn-N_(3)O-C catalyst,by reconstructing Mn sites into Mn(^(*)OH),the Mn sites were passivated and carbon sites adjacent to the O atom were verified to be the actual active sites by in situ characterization and theoretical calculation.Consequently,Mn-N_(3)O-C exhibited>80%Faradaic efficiency and superior long-term durability over 100 h for H_(2)O_(2)electrosynthesis at~120 mA cm^(-2).In addition,coupling anodic ethylene glycol oxidation reaction(EGOR)further improves the efficiency and economic viability of the H_(2)O_(2)electrosynthesis system.This two-pronged strategy thus opens up a new opportunity for the development of stable H_(2)O_(2)electrosynthesis with low energy consumption and superior economic performance.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.22305071,52472200,52271176,and52072114)the 111 Project(Grant No.D17007)+3 种基金Henan Center for Outstanding Overseas Scientists(Grant No.GZS2022017)the China Postdoctoral Science Foundation(Grant No.2022M721049)the Henan Province Key Research and Development Project(Grant No.231111520500)the Natural Science Foundation of Henan Province(Grant No.252300421556)。
文摘Development of high-efficiency bifunctional oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)electrocatalysts is vital for the widespread application of zinc-air batteries(ZABs).However,it still remains a great challenge to avoid the inhomogeneous distribution and aggregation of metal single-atomic active centers in the construction of bifunctional electrocatalysts with atomically dispersed multimetallic sites because of the common calcination method.Herein,we report a novel catalyst with phthalocyanine-assembled Fe-Co-Ni single-atomic triple sites dispersed on sulfur-doped graphene using a simple ultrasonic procedure without calcination,and X-ray absorption fine structure(XAFS),aberration-corrected scanning transmission electron microscopy(AC-STEM),and other detailed characterizations are performed to demonstrate the successful synthesis.The novel catalyst shows extraordinary bifunctional ORR/OER activities with a fairly low potential difference(ΔE=0.621 V)between the OER overpotential(Ej10=315 mV at 10 m A cm^(-2))and the ORR half-wave potential(Ehalf-wave=0.924 V).Moreover,the above catalyst shows excellent ZAB performance,with an outstanding specific capacity(786 mAh g^(-1)),noteworthy maximum power density(139 mW cm^(-2)),and extraordinary rechargeability(discharged and charged at 5 mA cm^(-2) for more than 1000 h).Theoretical calculations reveal the vital importance of the preferable synergetic coupling effect between adjacent active sites in the Fe-Co-Ni trimetallic single-atomic sites during the ORR/OER processes.This study provides a new avenue for the investigation of bifunctional electrocatalysts with atomically dispersed trimetallic sites,which is intended for enhancing the ORR/OER performance in ZABs.
基金funded by the European Union via the Euratom Research and Training Program(Grant Agreement No.101052200-EUROfusion)funding from LASERLAB-EUROPE(Grant Agreement No.871124,European Union’s Horizon 2020 Research and Innovation Program)+5 种基金supported in part by the United States Department of Energy under Grant No.DE-FG02-93ER40773We also acknowledge support from Grant No.PID2021-125389OA-I00 funded by MCIN/AEI/10.13039/501100011033/FEDER,UEby“ERDF A Way of Making Europe”by the European Union and Unidad de Investigación Consolidada of Junta de Castilla y León UIC 167supported in part by the National Natural Science Foundation of China under Grant No.12375125the Fundamental Research Funds for the Central Universitiesthe support of the Czech Science Foundation through Grant No.GACR24-11398S.
文摘Driving of the nuclear fusion reaction p+^(11)B3α+8.7 MeV under laboratory conditions by interaction between high-power laser pulses and matter has become a popular field of research,owing to its numerous potential applications:as an alternative to deuterium-tritium for fusion energy production,astrophysics studies,and alpha-particle generation for medical treatment.One possible scheme for laser-driven p-^(11)B reactions is to direct a beam of laser-accelerated protons onto a boron(B)sample(the so-called“pitcher-catcher”scheme).This technique has been successfully implemented on large high-energy lasers,yielding hundreds of joules per shot at low repetition.We present here a complementary approach,exploiting the high repetition rate of the VEGA III petawatt laser at CLPU(Spain),aiming at accumulating results from many interactions at much lower energy,to provide better control of the parameters and the statistics of the measurements.Despite a moderate energy per pulse,our experiment allowed exploration of the laser-driven fusion process with tens(up to hundreds)of laser shots.The experiment provided a clear signature of the reactions involved and of the fusion products,accumulated over many shots,leading to an improved optimization of the diagnostics for experimental campaigns of this type.In this paper,we discuss the effectiveness of laser-driven p-11B fusion in the pitcher-catcher scheme,at a high repetition rate,addressing the challenges of this experimental scheme and highlighting its critical aspects.Our proposed methodology allows evaluation of the performance of this scheme for laser-driven alpha particle production and can be adapted to high-repetition-rate laser facilities with higher energy and intensity.
文摘Hydrogen evolution reaction(HER)is unavoidable in many electrochemical synthesis systems,such as CO_(2)reduction,N2reduction,and H_(2)O_(2)synthesis.It makes those electrochemical reactions with multiple electron-proton transfers more complex when determining kinetics and mass transfer information.Understanding how HER competes with other electrochemical reduction reactions is crucial for both fundamental studies and system performance improvements.In this study,we employed the oxygen reduction reaction(ORR)as a model reaction to investigate HER competition on a polycrystalline-Au surface,using a rotating ring and disk electrode.It’s proved that water molecules serve as the proton source for ORR in alkaline,neutral,and even acidic electrolytes,and a 4-electron process can be achieved when the overpotential is sufficiently high.The competition from H⁺reduction becomes noticeable at the H⁺concentration higher than 2 mmol L^(–1)and intensi-fies as the H^(+)concentration increases.Based on the electrochemical results,we obtained an equivalent circuit diagram for the ORR system with competition from the H+reduction reaction,showing that these reactions occur in parallel and compete with each other.Electrochemical impedance spectroscopy measurements further confirm this argument.Additionally,we discover that the contribution of H+mass transfer to the total H^(+)reduction current is significant and comparable to the kinetic current.We believe this work will deepen our understanding of HER and its competition in electrochemical reduction systems.
基金supported by the Development Project of Youth Innovation Team in Shandong Colleges and Universities(No.2019KJC031)the Natural Science Foundation of Shandong Province(Nos.ZR2019MB064,ZR2021MB122 and ZR2022MB137)the Doctoral Program of Liaocheng University(No.318051608).
文摘Pt-based materials are the benchmarked catalysts in the cathodic hydrogen evolution reaction(HER)of water splitting;the prohibitive cost and scarcity of Pt immensely impede the commercialization of hydrogen energy.Ru has aroused significant concern because of its Pt-like activity and much lower price.However,it’s still a top priority to minimize the Ru loading and pursue the most superior cost performance.
基金sponsored by Major Science and Technology Project of the Yunnan Provincial Department of Science and Technology(202502AB080011)Yunnan Province Industrial High-Tech Project(202403AA080015)Special Science and Technology Research Project of Yunnan Province for the South Asia and Southeast Asia Innovation Center(202403AP140006).
文摘Ag/Al_(2)O_(3) powders are highly effective catalytic materials utilized in the epoxidation of ethylene to produce ethylene oxide.One of the critical challenges in this catalytic process is the stability of nano-sized Ag particles,especially during high-temperature catalysis.However,this issue can be effectively addressed through in-situ reaction synthesis.To gain a deeper understanding of the underlying mechanisms,the phase transformation process and the thermodynamic mechanism of the oxidation reaction in the Ag/Al_(2)O_(3) system have been investigated using firstprinciples thermodynamic calculations in conjunction with traditional thermodynamic data.These calculations,whose accuracy has been verified,provide valuable insights into the behavior of Ag and Al under different conditions.The results indicate that,during AgAl solid-solution oxidation,Ag-containing Al preferentially forms the stable intermediate phase Ag2Al instead of undergoing direct oxidation;this pathway becomes thermodynamically more favorable at higher Ag concentrations.With increasing temperature,Ag2Al is further oxidized to yield Ag and Al_(2)O_(3).It is also found that above 237℃,Ag2O and AgAlO2 become unstable.The overall reaction pathway is solid solution→Ag2Al→Ag+Al_(2)O_(3).This comprehensive study provides a robust theoretical calculation basis for the development and optimization of in-situ reaction-synthesized Ag/Al_(2)O_(3) powder composite materials,which have significant potential for practical applications in catalysis.
