Lithium-sulfur (Li-S) batteries have gained great attention due to the high theoretical energy density and low cost,yet their further commercialization has been obstructed by the notorious shuttle effect and sluggish ...Lithium-sulfur (Li-S) batteries have gained great attention due to the high theoretical energy density and low cost,yet their further commercialization has been obstructed by the notorious shuttle effect and sluggish redox dynamics.Herein,we supply a strategy to optimize the electron structure of Ni_(2)P by concurrently introducing B-doped atoms and P vacancies in Ni_(2)P (Vp-B-Ni_(2)P),thereby enhancing the bidirectional sulfur conversion.The study indicates that the simultaneous introduction of B-doped atoms and P vacancies in Ni_(2)P causes the redistribution of electron around Ni atoms,bringing about the upward shift of d-band center of Ni atoms and effective d-p orbital hybridization between Ni atoms and sulfur species,thus strengthening the chemical anchoring for lithium polysulfides (LiPSs) as well as expediting the bidirectional conversion kinetics of sulfur species.Meanwhile,theoretical calculations reveal that the incorporation of B-doped atoms and P vacancies in Ni_(2)P selectively promotes Li2S dissolution and nucleation processes.Thus,the Li-S batteries with Vp-B-Ni_(2)P-separators present outstanding rate ability of 777 m A h g^(-1)at 5 C and high areal capacity of 8.03 mA h cm^(-2)under E/S of 5μL mg^(-1)and sulfur loading of 7.20 mg cm^(-2).This work elucidates that introducing heteroatom and vacancy in metal phosphide collaboratively regulates the electron structure to accelerate bidirectional sulfur conversion.展开更多
Atmospheric escape plays a critical role in shaping the long-term climate evolution of Mars.Among the various escape mechanisms,energetic neutral atoms(ENAs)generated through charge exchange between solar wind ions an...Atmospheric escape plays a critical role in shaping the long-term climate evolution of Mars.Among the various escape mechanisms,energetic neutral atoms(ENAs)generated through charge exchange between solar wind ions and exospheric neutrals serve as an important diagnostic for ion-neutral interactions and upper atmospheric loss.This study presents direct observations of hydrogen ENAs(H-ENAs)on the dayside of Mars by using the Mars Ion and Neutral Particle Analyzer(MINPA)onboard China’s Tianwen-1 orbiter.By analyzing H-ENA data during a coronal mass ejection and a stream interaction region from December 29,2021,to January 1,2022,and comparing these data with MAVEN/SWIA(Mars Atmosphere and Volatile EvolutioN/Solar Wind Ion Analyzer)solar wind measurements,we examine the temporal evolution of H-ENA flux and the associated sputtered escape of atmospheric constituents.The observed H-ENA velocity is consistent with upstream solar wind ions,and the H-ENA-to-ion intensity ratio is used to infer variations in exospheric density,revealing a delayed response to enhanced solar wind activity.Penetrating H-ENA intensities reach up to 5.3×10^(6)s^(−1) cm^(−2),with energy fluxes on the order of(0.5-8.1)×10^(−3) mW/m^(2).The estimated oxygen sputtered escape rate driven by penetrating H-ENAs ranges from 5.5×10^(23)s^(−1) to 5.2×10^(24)s^(−1),comparable to or exceeding previous estimates based on penetrating ions.The findings highlight the need for low-altitude H-ENA observations to better quantify their atmospheric interactions and refine our understanding of nonthermal escape processes at Mars.展开更多
The photocatalytic oxidation of methane to methanol using molecule oxygen directly is an attractive catalytic reaction,but designing catalysts to avoid over-oxidation remains a significant challenge.Herein,Cu single-a...The photocatalytic oxidation of methane to methanol using molecule oxygen directly is an attractive catalytic reaction,but designing catalysts to avoid over-oxidation remains a significant challenge.Herein,Cu single-atom anchored on the defective carbon nitride structure(Cu SA/Def-CN)is designed for selective photocatalytic oxidation of methane into methanol using O_(2) under mild conditions.The Cu SA/Def-CN catalyst exhibits a high methanol selectivity of 92.8%under optimized conditions.Mechanistic studies reveal a synergistic effect between Def-CN and Cu SA,where Def-CN is responsible for the in-situ generation of hydrogen peroxide,which is subsequently decomposed by the Cu SA sites to produce·OH radicals that play a key role in the rate-determining step of methane activation to form methanol.Additionally,the presence of Cu SA not only enhances the electron-hole separation efficiency and improves the transfer of the photo-generated charges,but also increases the number of active sites for methane adsorption and activation.These insights provide valuable guidance for designing efficient catalysts for the highly selective photocatalytic oxidation of methane to methanol.展开更多
This study presents an achievement of laser cooling of alkaline-earth atoms in the Chinese Space Station’s strontium(Sr)atomic space optical clock.The system’s core components,physical unit,optical unit,and electric...This study presents an achievement of laser cooling of alkaline-earth atoms in the Chinese Space Station’s strontium(Sr)atomic space optical clock.The system’s core components,physical unit,optical unit,and electrical unit,have a total volume of 306 L and a total mass of 163.8 kg.These compact and robust units can overcome mechanical vibrations and temperature fluctuations during space launch.The laser sources of the optical unit are composed of diode lasers,and the injection locking of slave lasers is automatically performed by a program.In the experiment,a blue magneto-optical trap of cold atoms was achieved,with the atom numbers estimated to be approximately(1.50±0.13)×10^(6) for 87Sr and(8.00±0.56)×10^(6) for 88Sr.This work establishes a foundation for atomic confinement and high-precision interrogation in space-based optical clocks and expands the frontiers of cold atom physics in microgravity.展开更多
Conversion between different types of entangled states is an interesting problem in quantum mechanics.But research on the conversion between the Greenberger-Horne-Zeilinger(GHZ)state and Knill-Laflamme-Milburn(KLM)sta...Conversion between different types of entangled states is an interesting problem in quantum mechanics.But research on the conversion between the Greenberger-Horne-Zeilinger(GHZ)state and Knill-Laflamme-Milburn(KLM)state in an atomic system has not been reported.In this paper,we propose a scheme to realize the interconversion(one-step)between the GHZ state and KLM state with Rydberg atoms.By utilizing Rydberg-mediated interactions,we simplify the system.By combining a Lie-transform-based pulse design,the evolution path is built up to realize interconversion of the GHZ state and KLM state.The numerical simulation result shows that the present scheme is robust against decoherence and operational imperfection.展开更多
Platinum-based(Pt)catalysts are notoriously susceptible to deactivation in industrial chemical processes due to carbon monoxide(CO)poisoning.Overcoming this poisoning deactivation of Pt-based catalysts while enhancing...Platinum-based(Pt)catalysts are notoriously susceptible to deactivation in industrial chemical processes due to carbon monoxide(CO)poisoning.Overcoming this poisoning deactivation of Pt-based catalysts while enhancing their catalytic activity,selectivity,and durability remains a major challenge.Herein,we propose a strategy to enhance the CO tolerance of Pt clusters(Pt_n)by introducing neighboring functionalized vip single atoms(such as Fe,Co,Ni,Cu,Sb,and Bi).Among them,antimony(Sb)single atoms(SAs)exhibit significant performance enhancement,achieving 99%CO selectivity and 33.6%CO_(2)conversion at 450℃,Experimental results and density functional theory(DFT)calculations indicate the optimization arises from the electronic interaction between neighboring functionalized Sb SAs and Pt clusters,leading to optimal 5d electron redistribution in Pt clusters compared to other functionalized vip single atoms.The redistribution of 5d electrons weaken both theσdonation andπbackdonation interactions,resulting in a weakened bond strength with CO and enhancing catalyst activity and selectivity.In situ environmental transmission electron microscopy(ETEM)further demonstrates the exception thermal stability of the catalyst,even under H_(2)at 700℃.Notably,the functionalized Sb SAs also improve CO tolerance in various heterogenous catalysts,including Co/CeO_(2),Ni/CeO_(2),Pt/Al_(2)O_(3),and Pt/CeO_(2)-C.This finding provides an effective approach to overcome the primary challenge of CO poisoning in Pt-based catalysts,making their broader applications in various industrial catalysts.展开更多
The employment of single atom catalysts(SACs)remarkably increases atomic utilization and catalytic efficiency in various electrochemical processes,especially when coupled with metal clusters/nanoparticles.However,the ...The employment of single atom catalysts(SACs)remarkably increases atomic utilization and catalytic efficiency in various electrochemical processes,especially when coupled with metal clusters/nanoparticles.However,the synergistic effects mainly focus on the energetics of key intermediates during the electrocatalysis,while the properties of electrode surface and electric-double-layer(EDL)structure are largely overlooked.Herein,we report the synthesis of Ru nanoparticles integrated with neighboring Ru single atoms on nitrogen doped carbon(Ru1,n/NC)as efficient catalysts toward hydrogen oxidation reaction(HOR)under alkaline electrolytes.Electrochemical data,in situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy,and density functional theory calculations reveal that the positively charged Ru single atoms could lead to the dynamically regulated proportion of strongly hydrogen-bonded interfacial water structure with O-down conformation and optimized connectivity of the hydrogen-bond network in the EDL region,which contribute to the accelerated diffusion of hydroxide ions to the electrified interfaces.Consequently,the obtained Ru1,n/NC catalyst displays remarkable HOR performance with the mass activity of 1.15 mAμgPGM^(-1) under alkaline electrolyte.This work demonstrates the promise of single atoms for interfacial water environment adjustment and mass transfer process modulation,providing new insights into rational design of highly-effective SAC-based electrocatalysts.展开更多
We present the experimental demonstration of nondestructive detection of ^(171)Yb atoms in a magneto-optical trap(MOT) based on phase shift measurement induced by the atoms on a weak off-resonant laser beam. After loa...We present the experimental demonstration of nondestructive detection of ^(171)Yb atoms in a magneto-optical trap(MOT) based on phase shift measurement induced by the atoms on a weak off-resonant laser beam. After loading a green MOT of ^(171)Yb atoms, the phase shift is obtained with a two-color Mach–Zehnder interferometer by means of ±45 MHz detuning with respect to the ^(1)S_(0)–^(1)P_(1) transition. We measured a phase shift of about 100 mrad corresponding to an atom count of around 5 × 10^(5). This demonstrates that it is possible to obtain the number of atoms without direct destructive measurement compared with the absorption imaging method. This scheme could be an important approach towards a high-precision lattice clock for clock operation through suppression of the impact of the Dick effect.展开更多
Synergistic interplays involving multiple active centers originating from TiO2 nanotube layers(TNT)and ruthenium(Ru)species comprising of both single atoms(SAs)and nanoparticles(NPs)augment the alkaline hydrogen evolu...Synergistic interplays involving multiple active centers originating from TiO2 nanotube layers(TNT)and ruthenium(Ru)species comprising of both single atoms(SAs)and nanoparticles(NPs)augment the alkaline hydrogen evolution reaction(HER)by enhancing Volmer kinetics from rapid water dissociation and improving Tafel kinetics from efficient H*desorption.Atomic layer deposition of Ru with 50 process cycles results in a mixture of Ru SAs and 2.8-0.4 nm NPs present on TNT layers,and it emerges with the highest HER activity among all the electrodes synthesized.A detailed study of the Ti and Ru species using different high-resolution techniques confirmed the presence of Ti^(3+)states and the coexistence of Ru SAs and NPs.With insights from literature,the role of Ti^(3+),appropriate work functions of TNT layers and Ru,and the synergistic effect of Ru SAs and Ru NPs in improving the performance of alkaline HER were elaborated and justified.The aforementioned characteristics led to a remarkable performance by having 9mV onset potentials and 33 mV dec^(-1) of Tafel slopes and a higher turnover frequency of 1.72 H2 s^(-1) at 30 mV.Besides,a notable stability from 28 h staircase chronopotentiometric measurements for TNT@Ru surpasses TNT@Pt in comparison.展开更多
The synergy of single atoms(SAs)and nanoparticles(NPs)has demonstrated great potential in promoting the electrocatalytic carbon dioxide reduction reaction(CO_(2)RR);however,the rationalization of the SAs/NPs proportio...The synergy of single atoms(SAs)and nanoparticles(NPs)has demonstrated great potential in promoting the electrocatalytic carbon dioxide reduction reaction(CO_(2)RR);however,the rationalization of the SAs/NPs proportion remains one challenge for the catalyst design.Herein,a Ni2+-loaded porous poly(ionic liquids)(PIL)precursor synthesized through the free radical self-polymerization of the ionic liquid monomer,1-allyl-3-vinylimidazolium chloride,was pyrolyzed to prepare the Ni,N co-doped carbon materials,in which the proportion of Ni SAs and NPs could be facilely modulated by controlling the annealing temperature.The catalyst Ni-NC-1000 with a moderate proportion of Ni SAs and NPs exhibited high efficiency in the electrocatalytic conversion of CO_(2)into CO.Operando Ni K-edge X-ray absorption near-edge structure(XANES)spectra and theoretical calculations were conducted to gain insight into the synergy of Ni SAs and NPs.The charge transfer from Ni NPs to the surrounding carbon layer and then to the Ni SAs resulted in the electron-enriched Ni SAs active sites.In the electroreduction of CO_(2),the coexistence of Ni SAs and NPs strengthened the CO_(2)activation and the affinity towards the key intermediate of*COOH,lowering the free energy for the potential-determining*CO_(2)→*COOH step,and therefore promoted the catalysis efficiency.展开更多
Concurrent activation of lattice oxygen(O_L)and molecular oxygen(O_(2))is crucial for the efficient catalytic oxidation of biomass-derived molecules over metal oxides.Herein,we report that the introduction of ultralow...Concurrent activation of lattice oxygen(O_L)and molecular oxygen(O_(2))is crucial for the efficient catalytic oxidation of biomass-derived molecules over metal oxides.Herein,we report that the introduction of ultralow-loading of Ru single atoms(0.42 wt%)into Mn_(2)O_(3)matrix(0.4%Ru-Mn_(2)O_(3))greatly boosts its catalytic activity for the aerobic oxidation of 5-hydroxymethylfurfural(HMF)to 2,5-furandicarboxylic acid(FDCA).The FDCA productivity over the 0.4%Ru-Mn_(2)O_(3)(5.4 mmol_(FDCA)g_(cat)h^(-1))is 4.9 times higher than the Mn_(2)O_(3).Especially,this FDCAproductivity is also significantly higher than that of existing Ru and Mn-based catalysts.Experimental and theoretical investigations discovered that the Ru single atom facilitated the formation of oxygen vacancy(O_(v))in the catalyst,which synergistically weakened the Mn-O bond and promoted the activation of O_L.The co-presence of Ru single atoms and O_(v)also promote the adsorption and activation of both O_(2)and HMF.Consequently,the dehydrogenation reaction energy barrier of the rate-determining step was reduced via both the O_L and chemisorbed O_(2)dehydrogenation pathways,thus boosting the catalytic oxidation reactions.展开更多
We propose a scheme for dual-species deceleration and trapping of a cold atom–molecule mixture by a frequency chirping stimulated force.We study the stimulated force exerted on Mg F and Rb using optical Bloch equatio...We propose a scheme for dual-species deceleration and trapping of a cold atom–molecule mixture by a frequency chirping stimulated force.We study the stimulated force exerted on Mg F and Rb using optical Bloch equations based on a direct numerical solution for the time-dependent density matrix.We analyze the relationship between the frequency chirping rate and the number of Mg F molecules and Rb atoms.In addition,we study the dynamical process of molecular deceleration and the effect of transverse diffusion.Monte–Carlo simulations show that buffer-gas-cooled Mg F and Rb beams,with initial velocities of 200 m/s and 130 m/s respectively,can be decelerated to less than 10 m/s.This is achieved with laser powers of as low as 357 m W for Mg F and 10 m W for Rb per traveling wave.The rapid deceleration minimizes molecular loss due to transverse diffusion during the deceleration process.The estimated number of molecules that can be trapped in a magneto-optical trap(MOT)is about 9.0×10^(6),which is an order of magnitude larger than the number of Mg F molecules decelerated by the spontaneous radiation force.The results offer a promising starting point for further studies of sympathetic cooling.展开更多
Exploration of stable metal single-site supported porous graphitic carbon nitride(PCN)nanostructures and the development of maximum atom utilization for enhanced photocatalytic oxidation of antibiotics remains a chall...Exploration of stable metal single-site supported porous graphitic carbon nitride(PCN)nanostructures and the development of maximum atom utilization for enhanced photocatalytic oxidation of antibiotics remains a challenge in current research.This work proposed a one-step thermal copolymerization to obtain Cu(Ⅰ)doping porous carbon nitride(CUCN)through a spontaneously reducing atmosphere by urea in a covered crucible.The obtained CUCN had crumpled ultrathin nanosheets and mesoporous structures,which possessed higher specific surface areas than PCN.From X-ray absorption near edge structure(XANES)and Fourier transform extended X-ray absorption fine structure(FT-EXAFS)spectra analysis,the Cu doping existed in the oxidation state of Cu(Ⅰ)as single atoms anchored on the 2D layers of CN through two N neighbors,thereby facilitating efficient pathways for the transfer of photoexcited charge carriers.Furthermore,the photoluminescence(PL)spectra,electrochemical impedance spectra(EIS)and transient photocurrent response test proved the improved separation and transfer of photoexcited charge carriers for Cu(Ⅰ)introduction.Consequently,the photocatalytic activity of CUCN was much better than that of PCN for antibiotics norfloxacin(NOR),with 4.7-fold higher degradation reaction rate constants.From species-trapping experiments and density function theory(DFT)calculations,the Cu single atoms in Cu-N_(2)served as catalytic sites that could accelerate charge transfer and facilitate the adsorption of molecular oxygen to produce active species.The stable Cu(Ⅰ)embedded in the layer structure led to the excellent recycling test and remained stable after four runs of degradation and even thermal regenerated treatment.The degradation paths of NOR by CUCN under visible light were also demonstrated.Our work sheds light on a sustainable and practical approach for achieving stable metal single-atom doping and enhancing photocatalytic degradation of aqueous pollutants.展开更多
The development of single atom catalysts(SACs)with asymmetric active sites by defect regulation provides an encourage potential for oxygen reduction reaction(ORR)and hydrogen evolution reaction(HER),but highly challen...The development of single atom catalysts(SACs)with asymmetric active sites by defect regulation provides an encourage potential for oxygen reduction reaction(ORR)and hydrogen evolution reaction(HER),but highly challenging.Herein,N-doped carbon(N-C)anchored atomically dispersed Ni-N_(3)site with proximity defects(Ni-N_(3)D)induced by Te atoms doping is reported.Benefitting from the inductive effect of proximity defect,the Ni-N_(3)D/Te-N-C catalyst performs excellent ORR and HER performance in alkaline and acid condition.Both in situ characterization and theoretical calculation reveal that the existence of proximity defect effect is conducive to lower rate-determining-step energy barrier of ORR and HER,thus accelerating the multielectron reaction kinetics.This work paves a novel strategy for constructing highactivity bifunctional SACs by defect engineering for development of sustainable energy.展开更多
Plastics are ubiquitous in human life and pose certain hazards to the environment and human body.The increasing amount of CO_(2)in the atmosphere will lead to the greenhouse effect.Therefore,it is urgent to treat micr...Plastics are ubiquitous in human life and pose certain hazards to the environment and human body.The increasing amount of CO_(2)in the atmosphere will lead to the greenhouse effect.Therefore,it is urgent to treat microplastic waste and CO_(2)by using environmentally friendly and efficient technologies.In this work,we developed an efficient photoelectrocatalytic system composed of Ni single atoms(Ni SAs)supported by P,N-doped amorphous NiFe_(2)O_(4)(Ni SAs/A-P-N-NFO)as anode and Ag nanoparticles(Ag NPs)supported by CuO/Cu_(2)O nanocubes(Ag NPs@CuO/Cu_(2)O NCs)as cathode for microplastic oxidation and CO_(2)reduction.The Ni SAs/A-P-N-NFO was synthesized by calcination-H_(2)reduction method,and it achieved a Faraday efficiency of 93%for the oxidation reaction of poly(ethylene terephthalate)(PET)solution under AM 1.5 G light.As a photocathode,the synthesized Ag NPs@CuO/Cu_(2)O NCs was utilized to reduce CO_(2)to ethylene and CO at 1.5 V vs.RHE with selectivity of 42%and 55%,respectively.This work shows that the photoelectrocatalysis,as an environmentally friendly technology,is a feasible strategy for reducing the environmental and biological hazards of light plastics,as well as for efficient CO_(2)reduction.展开更多
Combining single atoms with clusters or nanoparticles is an emerging tactic to design efficient electrocatalysts.Both synergy effect and high atomic utilization of active sites in the composite catalysts result in enh...Combining single atoms with clusters or nanoparticles is an emerging tactic to design efficient electrocatalysts.Both synergy effect and high atomic utilization of active sites in the composite catalysts result in enhanced electrocatalytic performance,simultaneously provide a radical analysis of the interrelationship between structure and activity.In this review,the recent advances of single-atomic site catalysts coupled with clusters or nanoparticles are emphasized.Firstly,the synthetic strategies,characterization,dynamics and types of single atoms coupled with clusters/nanoparticles are introduced,and then the key factors controlling the structure of the composite catalysts are discussed.Next,several clean energy catalytic reactions performed over the synergistic composite catalysts are illustrated.Eventually,the encountering challenges and recommendations for the future advancement of synergistic structure in energy-transformation electrocatalysis are outlined.展开更多
Ti-based catalysts are known to improve the hydrogen storage performance of NaAlH4by facilitating the dissociation/recombination of H-H and Al-H bonds.The catalytic activity of metallic Ti species strongly depends on ...Ti-based catalysts are known to improve the hydrogen storage performance of NaAlH4by facilitating the dissociation/recombination of H-H and Al-H bonds.The catalytic activity of metallic Ti species strongly depends on its particle size and dispersity.Ti clusters and even single atoms are therefore highly desirable,but their controllable fabrication has been highly challenging.He rein,we demonstrate a novel facile sonochemical synthesis of a Ti-O clusters featuring single Ti atom catalyst at room temperature.Through reducing TiCl_(4)by MgBu_(2)with ultrasound instead of heating as driving force,numerous single Ti atoms coupled with Ti-O clusters with Ti loading on graphene(Ti_(1)/Ti-O@G)up to 22.6 wt%have been successfully obtained.The prepared Ti_(1)/Ti-O@G contributes high reactivity and superior catalytic activity,therefore enabling full dehydrogenation of NaAlH_(4)at 80℃in thermogravimetric mode and re-hydrogenation at 30℃and 10 MPa with 4.9 wt% H_(2).This fact indicates for the first time that single Ti atom catalyst with high loading is highly effective in catalyzing hydrogen cycling of NaAlH4at remarkably reduced temperatures.展开更多
Strategically designing the electrocatalytic system and cleverly inducing strain is an effective approach to balance the cost and activity of Pt-based electrocatalysts for industrial-scale hydrogen production.Herein,w...Strategically designing the electrocatalytic system and cleverly inducing strain is an effective approach to balance the cost and activity of Pt-based electrocatalysts for industrial-scale hydrogen production.Herein,we present a unipolar pulsed electrodeposition(UPED) strategy to induce strain in the Ni lattice by introducing trace amounts of Pt single atoms(SAs)(0.22 wt%).The overpotential decreased by 183 mV at 10 mA cm^(-2) in 1.0 M KOH after introducing trace amounts of Pt_(SAs).The industrial electrolyzer,assembled with Pt_(SAs)Ni cathode and a commercial NiFeO_(x) anode,requires a cell voltage of 1.90 V to attain 1 A cm^(-2) of current density and remains stable for 280 h,demonstrating significant potential for practical applications.Spherical aberration corrected scanning transmission electron microscopy(AC-STEM),X-ray absorption(XAS),and geometric phase analysis(GPA) indicate that the introduction of trace amounts of Pt SAs induces tensile strain in the Ni lattice,thereby altering the local electronic structure and coordination environment around cubic Ni for enhancing the water decomposition kinetics and fundamentally changing the reaction pathway.The doping-strain strategy showcases conformational relationships that could offer new ideas to construct efficient hydrogen evolution reaction(HER) electrocatalysts for industrial hydrogen production in the future.展开更多
Single-atom materials have demonstrated attractive physicochemical characteristics.However,understanding the relationships between the coordination environment of single atoms and their properties at the atomic level ...Single-atom materials have demonstrated attractive physicochemical characteristics.However,understanding the relationships between the coordination environment of single atoms and their properties at the atomic level remains a considerable challenge.Herein,a facile waterassisted carbonization approach is developed to fabricate well-defined asymmetrically coordinated Co–N_(4)–O sites on biomass-derived carbon nanofiber(Co–N_(4)–O/NCF)for electromagnetic wave(EMW)absorption.In such nanofiber,one atomically dispersed Co site is coordinated with four N atoms in the graphene basal plane and one oxygen atom in the axial direction.In-depth experimental and theoretical studies reveal that the axial Co–O coordination breaks the charge distribution symmetry in the planar porphyrin-like Co–N_(4) structure,leading to significantly enhanced dielectric polarization loss relevant to the planar Co–N_(4) sites.Importantly,the film based on Co–N_(4)–O/NCF exhibits light weight,flexibility,excellent mechanical properties,great thermal insulating feature,and excellent EMW absorption with a reflection loss of−45.82 dB along with an effective absorption bandwidth of 4.8 GHz.The findings of this work offer insight into the relationships between the single-atom coordination environment and the dielectric performance,and the proposed strategy can be extended toward the engineering of asymmetrically coordinated single atoms for various applications.展开更多
Single-atom(SA)catalysts with nearly 100%atom utilization have been widely employed in electrolysis for decades,due to the outperforming catalytic activity and selectivity.However,most of the reported SA catalysts are...Single-atom(SA)catalysts with nearly 100%atom utilization have been widely employed in electrolysis for decades,due to the outperforming catalytic activity and selectivity.However,most of the reported SA catalysts are fixed through the strong bonding between the dispersed single metallic atoms with nonmetallic atoms of the substrates,which greatly limits the controllable regulation of electrocatalytic activity of SA catalysts.In this work,Pt-Ni bonded Pt SA catalyst with adjustable electronic states was successfully constructed through a controllable electrochemical reduction on the coordination unsaturated amorphous Ni(OH)_(2)nanosheet arrays.Based on the X-ray absorption fine structure analysis and first-principles calculations,Pt SA was bonded with Ni sites of amorphous Ni(OH)_(2),rather than conventional O sites,resulting in negatively charged Pt^(δ-).In situ Raman spectroscopy revealed that the changed configuration and electronic states greatly enhanced absorbability for activated hydrogen atoms,which were the essential intermediate for alkaline hydrogen evolution reaction.The hydrogen spillover process was revealed from amorphous Ni(OH)_(2)that effectively cleave the H-O-H bond of H_(2)O and produce H atom to the Pt SA sites,leading to a low overpotential of 48 mV in alkaline electrolyte at-1000 mA cm^(-2)mg^(-1)_(Pt),evidently better than commercial Pt/C catalysts.This work provided new strategy for the control-lable modulation of the local structure of SA catalysts and the systematic regulation of the electronic states.展开更多
基金Institute of Technology Research Fund Program for Young Scholars21C Innovation Laboratory Contemporary Amperex Technology Co.,Limited,Ninde, 352100, China (21C–OP-202314)。
文摘Lithium-sulfur (Li-S) batteries have gained great attention due to the high theoretical energy density and low cost,yet their further commercialization has been obstructed by the notorious shuttle effect and sluggish redox dynamics.Herein,we supply a strategy to optimize the electron structure of Ni_(2)P by concurrently introducing B-doped atoms and P vacancies in Ni_(2)P (Vp-B-Ni_(2)P),thereby enhancing the bidirectional sulfur conversion.The study indicates that the simultaneous introduction of B-doped atoms and P vacancies in Ni_(2)P causes the redistribution of electron around Ni atoms,bringing about the upward shift of d-band center of Ni atoms and effective d-p orbital hybridization between Ni atoms and sulfur species,thus strengthening the chemical anchoring for lithium polysulfides (LiPSs) as well as expediting the bidirectional conversion kinetics of sulfur species.Meanwhile,theoretical calculations reveal that the incorporation of B-doped atoms and P vacancies in Ni_(2)P selectively promotes Li2S dissolution and nucleation processes.Thus,the Li-S batteries with Vp-B-Ni_(2)P-separators present outstanding rate ability of 777 m A h g^(-1)at 5 C and high areal capacity of 8.03 mA h cm^(-2)under E/S of 5μL mg^(-1)and sulfur loading of 7.20 mg cm^(-2).This work elucidates that introducing heteroatom and vacancy in metal phosphide collaboratively regulates the electron structure to accelerate bidirectional sulfur conversion.
基金supported by the National Natural Science Foundation of China (Grant Nos. 42188101, 42274211, 41974170, 42374184, 42122032, and 41974196)the Chinese Academy of Sciences (Grant Nos. QYZDJSSW-JSC028, XDA15052500, XDA17010301, and XDB41000000)+3 种基金the CNSA (Grant No. D050103)the Specialized Research Fund for State Key Laboratories of Chinathe Specialized Research Fund for Laboratory of Geospace Environment of the University of Science and Technology of Chinasupported by the International Space Science Institute (ISSI) in Bern and Beijing through the ISSI/ISSI-BJ International Team Project titled “Understanding the Mars Space Environment Through Multi-Spacecraft Measurements” (ISSI Team Project No. 23-582 and ISSI-BJ Team Project No. 58)
文摘Atmospheric escape plays a critical role in shaping the long-term climate evolution of Mars.Among the various escape mechanisms,energetic neutral atoms(ENAs)generated through charge exchange between solar wind ions and exospheric neutrals serve as an important diagnostic for ion-neutral interactions and upper atmospheric loss.This study presents direct observations of hydrogen ENAs(H-ENAs)on the dayside of Mars by using the Mars Ion and Neutral Particle Analyzer(MINPA)onboard China’s Tianwen-1 orbiter.By analyzing H-ENA data during a coronal mass ejection and a stream interaction region from December 29,2021,to January 1,2022,and comparing these data with MAVEN/SWIA(Mars Atmosphere and Volatile EvolutioN/Solar Wind Ion Analyzer)solar wind measurements,we examine the temporal evolution of H-ENA flux and the associated sputtered escape of atmospheric constituents.The observed H-ENA velocity is consistent with upstream solar wind ions,and the H-ENA-to-ion intensity ratio is used to infer variations in exospheric density,revealing a delayed response to enhanced solar wind activity.Penetrating H-ENA intensities reach up to 5.3×10^(6)s^(−1) cm^(−2),with energy fluxes on the order of(0.5-8.1)×10^(−3) mW/m^(2).The estimated oxygen sputtered escape rate driven by penetrating H-ENAs ranges from 5.5×10^(23)s^(−1) to 5.2×10^(24)s^(−1),comparable to or exceeding previous estimates based on penetrating ions.The findings highlight the need for low-altitude H-ENA observations to better quantify their atmospheric interactions and refine our understanding of nonthermal escape processes at Mars.
文摘The photocatalytic oxidation of methane to methanol using molecule oxygen directly is an attractive catalytic reaction,but designing catalysts to avoid over-oxidation remains a significant challenge.Herein,Cu single-atom anchored on the defective carbon nitride structure(Cu SA/Def-CN)is designed for selective photocatalytic oxidation of methane into methanol using O_(2) under mild conditions.The Cu SA/Def-CN catalyst exhibits a high methanol selectivity of 92.8%under optimized conditions.Mechanistic studies reveal a synergistic effect between Def-CN and Cu SA,where Def-CN is responsible for the in-situ generation of hydrogen peroxide,which is subsequently decomposed by the Cu SA sites to produce·OH radicals that play a key role in the rate-determining step of methane activation to form methanol.Additionally,the presence of Cu SA not only enhances the electron-hole separation efficiency and improves the transfer of the photo-generated charges,but also increases the number of active sites for methane adsorption and activation.These insights provide valuable guidance for designing efficient catalysts for the highly selective photocatalytic oxidation of methane to methanol.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB35010202)the National Natural Science Foundation of China(Grants No.62275268)。
文摘This study presents an achievement of laser cooling of alkaline-earth atoms in the Chinese Space Station’s strontium(Sr)atomic space optical clock.The system’s core components,physical unit,optical unit,and electrical unit,have a total volume of 306 L and a total mass of 163.8 kg.These compact and robust units can overcome mechanical vibrations and temperature fluctuations during space launch.The laser sources of the optical unit are composed of diode lasers,and the injection locking of slave lasers is automatically performed by a program.In the experiment,a blue magneto-optical trap of cold atoms was achieved,with the atom numbers estimated to be approximately(1.50±0.13)×10^(6) for 87Sr and(8.00±0.56)×10^(6) for 88Sr.This work establishes a foundation for atomic confinement and high-precision interrogation in space-based optical clocks and expands the frontiers of cold atom physics in microgravity.
基金supported by the Department of Education of Liaoning Province(Grant Nos.LJKZ1015,LJ2020005,LJKZZ20220120)the Natural Science Foundation of Liaoning Province(Grant Nos.2020-BS-234,2021-MS-317,2022-MS-372)the Program of Liaoning Bai Qian Wan Talents Program(Grant No.2021921096)。
文摘Conversion between different types of entangled states is an interesting problem in quantum mechanics.But research on the conversion between the Greenberger-Horne-Zeilinger(GHZ)state and Knill-Laflamme-Milburn(KLM)state in an atomic system has not been reported.In this paper,we propose a scheme to realize the interconversion(one-step)between the GHZ state and KLM state with Rydberg atoms.By utilizing Rydberg-mediated interactions,we simplify the system.By combining a Lie-transform-based pulse design,the evolution path is built up to realize interconversion of the GHZ state and KLM state.The numerical simulation result shows that the present scheme is robust against decoherence and operational imperfection.
基金financially supported by the Shanghai RisingStar Program(No.23QA1403700)the National Natural Science Foundation of China(NSFC,Grant No.U2230102)+1 种基金the sponsored by National Key Research and Development Program of China(No.2021YFB3502200)the Shanghai Technical Service Center of Science and Engineering Computing,Shanghai University.
文摘Platinum-based(Pt)catalysts are notoriously susceptible to deactivation in industrial chemical processes due to carbon monoxide(CO)poisoning.Overcoming this poisoning deactivation of Pt-based catalysts while enhancing their catalytic activity,selectivity,and durability remains a major challenge.Herein,we propose a strategy to enhance the CO tolerance of Pt clusters(Pt_n)by introducing neighboring functionalized vip single atoms(such as Fe,Co,Ni,Cu,Sb,and Bi).Among them,antimony(Sb)single atoms(SAs)exhibit significant performance enhancement,achieving 99%CO selectivity and 33.6%CO_(2)conversion at 450℃,Experimental results and density functional theory(DFT)calculations indicate the optimization arises from the electronic interaction between neighboring functionalized Sb SAs and Pt clusters,leading to optimal 5d electron redistribution in Pt clusters compared to other functionalized vip single atoms.The redistribution of 5d electrons weaken both theσdonation andπbackdonation interactions,resulting in a weakened bond strength with CO and enhancing catalyst activity and selectivity.In situ environmental transmission electron microscopy(ETEM)further demonstrates the exception thermal stability of the catalyst,even under H_(2)at 700℃.Notably,the functionalized Sb SAs also improve CO tolerance in various heterogenous catalysts,including Co/CeO_(2),Ni/CeO_(2),Pt/Al_(2)O_(3),and Pt/CeO_(2)-C.This finding provides an effective approach to overcome the primary challenge of CO poisoning in Pt-based catalysts,making their broader applications in various industrial catalysts.
文摘The employment of single atom catalysts(SACs)remarkably increases atomic utilization and catalytic efficiency in various electrochemical processes,especially when coupled with metal clusters/nanoparticles.However,the synergistic effects mainly focus on the energetics of key intermediates during the electrocatalysis,while the properties of electrode surface and electric-double-layer(EDL)structure are largely overlooked.Herein,we report the synthesis of Ru nanoparticles integrated with neighboring Ru single atoms on nitrogen doped carbon(Ru1,n/NC)as efficient catalysts toward hydrogen oxidation reaction(HOR)under alkaline electrolytes.Electrochemical data,in situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy,and density functional theory calculations reveal that the positively charged Ru single atoms could lead to the dynamically regulated proportion of strongly hydrogen-bonded interfacial water structure with O-down conformation and optimized connectivity of the hydrogen-bond network in the EDL region,which contribute to the accelerated diffusion of hydroxide ions to the electrified interfaces.Consequently,the obtained Ru1,n/NC catalyst displays remarkable HOR performance with the mass activity of 1.15 mAμgPGM^(-1) under alkaline electrolyte.This work demonstrates the promise of single atoms for interfacial water environment adjustment and mass transfer process modulation,providing new insights into rational design of highly-effective SAC-based electrocatalysts.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. U20A2075,11803072,and 12374467)the Innovation Program for Quantum Science and Technology (Grant No. 2021ZD0300902)the Hubei Provincial Science and Technology Major Project (Grant No. ZDZX2022000004)。
文摘We present the experimental demonstration of nondestructive detection of ^(171)Yb atoms in a magneto-optical trap(MOT) based on phase shift measurement induced by the atoms on a weak off-resonant laser beam. After loading a green MOT of ^(171)Yb atoms, the phase shift is obtained with a two-color Mach–Zehnder interferometer by means of ±45 MHz detuning with respect to the ^(1)S_(0)–^(1)P_(1) transition. We measured a phase shift of about 100 mrad corresponding to an atom count of around 5 × 10^(5). This demonstrates that it is possible to obtain the number of atoms without direct destructive measurement compared with the absorption imaging method. This scheme could be an important approach towards a high-precision lattice clock for clock operation through suppression of the impact of the Dick effect.
基金support from the European Union Horizon 2020 program(project HERMES,nr.952184)the Ministry of Education,Youth and Sports of the Czech Republic for supporting CEMNAT(LM2023037)+1 种基金Czech-NanoLab(LM2023051)infrastructures for providing ALD,SEM,EDX,XPS,TEM,and XRDCzech Science Foundation(project 23-08019X,EXPRO).
文摘Synergistic interplays involving multiple active centers originating from TiO2 nanotube layers(TNT)and ruthenium(Ru)species comprising of both single atoms(SAs)and nanoparticles(NPs)augment the alkaline hydrogen evolution reaction(HER)by enhancing Volmer kinetics from rapid water dissociation and improving Tafel kinetics from efficient H*desorption.Atomic layer deposition of Ru with 50 process cycles results in a mixture of Ru SAs and 2.8-0.4 nm NPs present on TNT layers,and it emerges with the highest HER activity among all the electrodes synthesized.A detailed study of the Ti and Ru species using different high-resolution techniques confirmed the presence of Ti^(3+)states and the coexistence of Ru SAs and NPs.With insights from literature,the role of Ti^(3+),appropriate work functions of TNT layers and Ru,and the synergistic effect of Ru SAs and Ru NPs in improving the performance of alkaline HER were elaborated and justified.The aforementioned characteristics led to a remarkable performance by having 9mV onset potentials and 33 mV dec^(-1) of Tafel slopes and a higher turnover frequency of 1.72 H2 s^(-1) at 30 mV.Besides,a notable stability from 28 h staircase chronopotentiometric measurements for TNT@Ru surpasses TNT@Pt in comparison.
基金National Natural Science Foundation of China(grants 22072065,22178162,and 22222806)Distinguished Youth Foundation of Jiangsu Province(grant BK20220053)Six talent peaks project in Jiangsu Province(grant JNHB-035)。
文摘The synergy of single atoms(SAs)and nanoparticles(NPs)has demonstrated great potential in promoting the electrocatalytic carbon dioxide reduction reaction(CO_(2)RR);however,the rationalization of the SAs/NPs proportion remains one challenge for the catalyst design.Herein,a Ni2+-loaded porous poly(ionic liquids)(PIL)precursor synthesized through the free radical self-polymerization of the ionic liquid monomer,1-allyl-3-vinylimidazolium chloride,was pyrolyzed to prepare the Ni,N co-doped carbon materials,in which the proportion of Ni SAs and NPs could be facilely modulated by controlling the annealing temperature.The catalyst Ni-NC-1000 with a moderate proportion of Ni SAs and NPs exhibited high efficiency in the electrocatalytic conversion of CO_(2)into CO.Operando Ni K-edge X-ray absorption near-edge structure(XANES)spectra and theoretical calculations were conducted to gain insight into the synergy of Ni SAs and NPs.The charge transfer from Ni NPs to the surrounding carbon layer and then to the Ni SAs resulted in the electron-enriched Ni SAs active sites.In the electroreduction of CO_(2),the coexistence of Ni SAs and NPs strengthened the CO_(2)activation and the affinity towards the key intermediate of*COOH,lowering the free energy for the potential-determining*CO_(2)→*COOH step,and therefore promoted the catalysis efficiency.
基金financially supported by National Natural Science Foundation of China(22208137 and 22068022)Yunnan Fundamental Research Projects(202101BE070001-033,202401AT070825,202201BE070001007 and 202301AV070005)。
文摘Concurrent activation of lattice oxygen(O_L)and molecular oxygen(O_(2))is crucial for the efficient catalytic oxidation of biomass-derived molecules over metal oxides.Herein,we report that the introduction of ultralow-loading of Ru single atoms(0.42 wt%)into Mn_(2)O_(3)matrix(0.4%Ru-Mn_(2)O_(3))greatly boosts its catalytic activity for the aerobic oxidation of 5-hydroxymethylfurfural(HMF)to 2,5-furandicarboxylic acid(FDCA).The FDCA productivity over the 0.4%Ru-Mn_(2)O_(3)(5.4 mmol_(FDCA)g_(cat)h^(-1))is 4.9 times higher than the Mn_(2)O_(3).Especially,this FDCAproductivity is also significantly higher than that of existing Ru and Mn-based catalysts.Experimental and theoretical investigations discovered that the Ru single atom facilitated the formation of oxygen vacancy(O_(v))in the catalyst,which synergistically weakened the Mn-O bond and promoted the activation of O_L.The co-presence of Ru single atoms and O_(v)also promote the adsorption and activation of both O_(2)and HMF.Consequently,the dehydrogenation reaction energy barrier of the rate-determining step was reduced via both the O_L and chemisorbed O_(2)dehydrogenation pathways,thus boosting the catalytic oxidation reactions.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12174115 and 91836103)。
文摘We propose a scheme for dual-species deceleration and trapping of a cold atom–molecule mixture by a frequency chirping stimulated force.We study the stimulated force exerted on Mg F and Rb using optical Bloch equations based on a direct numerical solution for the time-dependent density matrix.We analyze the relationship between the frequency chirping rate and the number of Mg F molecules and Rb atoms.In addition,we study the dynamical process of molecular deceleration and the effect of transverse diffusion.Monte–Carlo simulations show that buffer-gas-cooled Mg F and Rb beams,with initial velocities of 200 m/s and 130 m/s respectively,can be decelerated to less than 10 m/s.This is achieved with laser powers of as low as 357 m W for Mg F and 10 m W for Rb per traveling wave.The rapid deceleration minimizes molecular loss due to transverse diffusion during the deceleration process.The estimated number of molecules that can be trapped in a magneto-optical trap(MOT)is about 9.0×10^(6),which is an order of magnitude larger than the number of Mg F molecules decelerated by the spontaneous radiation force.The results offer a promising starting point for further studies of sympathetic cooling.
基金supported by the National Natural Science Foundation of China(Nos.52070103 and 22102102)Zhejiang Provincial Natural Science Foundation of China(Nos.LY21E090004 and LQ22B050004)+1 种基金Ningbo Public Welfare Science and Technology Program(No.2021S025)Ningbo Youth Leading Talent Project(No.2024QL038).
文摘Exploration of stable metal single-site supported porous graphitic carbon nitride(PCN)nanostructures and the development of maximum atom utilization for enhanced photocatalytic oxidation of antibiotics remains a challenge in current research.This work proposed a one-step thermal copolymerization to obtain Cu(Ⅰ)doping porous carbon nitride(CUCN)through a spontaneously reducing atmosphere by urea in a covered crucible.The obtained CUCN had crumpled ultrathin nanosheets and mesoporous structures,which possessed higher specific surface areas than PCN.From X-ray absorption near edge structure(XANES)and Fourier transform extended X-ray absorption fine structure(FT-EXAFS)spectra analysis,the Cu doping existed in the oxidation state of Cu(Ⅰ)as single atoms anchored on the 2D layers of CN through two N neighbors,thereby facilitating efficient pathways for the transfer of photoexcited charge carriers.Furthermore,the photoluminescence(PL)spectra,electrochemical impedance spectra(EIS)and transient photocurrent response test proved the improved separation and transfer of photoexcited charge carriers for Cu(Ⅰ)introduction.Consequently,the photocatalytic activity of CUCN was much better than that of PCN for antibiotics norfloxacin(NOR),with 4.7-fold higher degradation reaction rate constants.From species-trapping experiments and density function theory(DFT)calculations,the Cu single atoms in Cu-N_(2)served as catalytic sites that could accelerate charge transfer and facilitate the adsorption of molecular oxygen to produce active species.The stable Cu(Ⅰ)embedded in the layer structure led to the excellent recycling test and remained stable after four runs of degradation and even thermal regenerated treatment.The degradation paths of NOR by CUCN under visible light were also demonstrated.Our work sheds light on a sustainable and practical approach for achieving stable metal single-atom doping and enhancing photocatalytic degradation of aqueous pollutants.
基金financially supported by the National Natural Science Foundation of China(22478432,22108306,22178388)Taishan Scholars Program of Shandong Province(tsqn201909065)+2 种基金Shandong Provincial Natural Science Foundation(ZR2024JQ004)Innovation Fund Project for Graduate Student of China University of Petroleum(East China)the Fundamental Research Funds for the Central Universities(No.25CX04020A)。
文摘The development of single atom catalysts(SACs)with asymmetric active sites by defect regulation provides an encourage potential for oxygen reduction reaction(ORR)and hydrogen evolution reaction(HER),but highly challenging.Herein,N-doped carbon(N-C)anchored atomically dispersed Ni-N_(3)site with proximity defects(Ni-N_(3)D)induced by Te atoms doping is reported.Benefitting from the inductive effect of proximity defect,the Ni-N_(3)D/Te-N-C catalyst performs excellent ORR and HER performance in alkaline and acid condition.Both in situ characterization and theoretical calculation reveal that the existence of proximity defect effect is conducive to lower rate-determining-step energy barrier of ORR and HER,thus accelerating the multielectron reaction kinetics.This work paves a novel strategy for constructing highactivity bifunctional SACs by defect engineering for development of sustainable energy.
文摘Plastics are ubiquitous in human life and pose certain hazards to the environment and human body.The increasing amount of CO_(2)in the atmosphere will lead to the greenhouse effect.Therefore,it is urgent to treat microplastic waste and CO_(2)by using environmentally friendly and efficient technologies.In this work,we developed an efficient photoelectrocatalytic system composed of Ni single atoms(Ni SAs)supported by P,N-doped amorphous NiFe_(2)O_(4)(Ni SAs/A-P-N-NFO)as anode and Ag nanoparticles(Ag NPs)supported by CuO/Cu_(2)O nanocubes(Ag NPs@CuO/Cu_(2)O NCs)as cathode for microplastic oxidation and CO_(2)reduction.The Ni SAs/A-P-N-NFO was synthesized by calcination-H_(2)reduction method,and it achieved a Faraday efficiency of 93%for the oxidation reaction of poly(ethylene terephthalate)(PET)solution under AM 1.5 G light.As a photocathode,the synthesized Ag NPs@CuO/Cu_(2)O NCs was utilized to reduce CO_(2)to ethylene and CO at 1.5 V vs.RHE with selectivity of 42%and 55%,respectively.This work shows that the photoelectrocatalysis,as an environmentally friendly technology,is a feasible strategy for reducing the environmental and biological hazards of light plastics,as well as for efficient CO_(2)reduction.
基金financially supported by the National Natural Science Foundation of China(22279036)the Innovation Talent Recruitment Base of New Energy Chemistry Device(B21003)the Fundamental Research Funds for the Central Universities(no.2019kfyRCPY100).
文摘Combining single atoms with clusters or nanoparticles is an emerging tactic to design efficient electrocatalysts.Both synergy effect and high atomic utilization of active sites in the composite catalysts result in enhanced electrocatalytic performance,simultaneously provide a radical analysis of the interrelationship between structure and activity.In this review,the recent advances of single-atomic site catalysts coupled with clusters or nanoparticles are emphasized.Firstly,the synthetic strategies,characterization,dynamics and types of single atoms coupled with clusters/nanoparticles are introduced,and then the key factors controlling the structure of the composite catalysts are discussed.Next,several clean energy catalytic reactions performed over the synergistic composite catalysts are illustrated.Eventually,the encountering challenges and recommendations for the future advancement of synergistic structure in energy-transformation electrocatalysis are outlined.
基金financially supported by the National Outstanding Youth Foundation of China(No.52125104)the Natural Science Foundation of Zhejiang Province(No.LD21E010002)+2 种基金the National Natural Science Foundation of China(Nos.52071285 and 52001277)the Fundamental Research Funds for the Central Universities(Nos.2021FZZX001-09 and 226-202200246)the National Youth Top-Notch Talent Support Program。
文摘Ti-based catalysts are known to improve the hydrogen storage performance of NaAlH4by facilitating the dissociation/recombination of H-H and Al-H bonds.The catalytic activity of metallic Ti species strongly depends on its particle size and dispersity.Ti clusters and even single atoms are therefore highly desirable,but their controllable fabrication has been highly challenging.He rein,we demonstrate a novel facile sonochemical synthesis of a Ti-O clusters featuring single Ti atom catalyst at room temperature.Through reducing TiCl_(4)by MgBu_(2)with ultrasound instead of heating as driving force,numerous single Ti atoms coupled with Ti-O clusters with Ti loading on graphene(Ti_(1)/Ti-O@G)up to 22.6 wt%have been successfully obtained.The prepared Ti_(1)/Ti-O@G contributes high reactivity and superior catalytic activity,therefore enabling full dehydrogenation of NaAlH_(4)at 80℃in thermogravimetric mode and re-hydrogenation at 30℃and 10 MPa with 4.9 wt% H_(2).This fact indicates for the first time that single Ti atom catalyst with high loading is highly effective in catalyzing hydrogen cycling of NaAlH4at remarkably reduced temperatures.
基金National Natural Science Foundation of China (grants U22A20418, 22075196, and 21878204)Research Project Supported by Shanxi Scholarship Council of China (2022-050)。
文摘Strategically designing the electrocatalytic system and cleverly inducing strain is an effective approach to balance the cost and activity of Pt-based electrocatalysts for industrial-scale hydrogen production.Herein,we present a unipolar pulsed electrodeposition(UPED) strategy to induce strain in the Ni lattice by introducing trace amounts of Pt single atoms(SAs)(0.22 wt%).The overpotential decreased by 183 mV at 10 mA cm^(-2) in 1.0 M KOH after introducing trace amounts of Pt_(SAs).The industrial electrolyzer,assembled with Pt_(SAs)Ni cathode and a commercial NiFeO_(x) anode,requires a cell voltage of 1.90 V to attain 1 A cm^(-2) of current density and remains stable for 280 h,demonstrating significant potential for practical applications.Spherical aberration corrected scanning transmission electron microscopy(AC-STEM),X-ray absorption(XAS),and geometric phase analysis(GPA) indicate that the introduction of trace amounts of Pt SAs induces tensile strain in the Ni lattice,thereby altering the local electronic structure and coordination environment around cubic Ni for enhancing the water decomposition kinetics and fundamentally changing the reaction pathway.The doping-strain strategy showcases conformational relationships that could offer new ideas to construct efficient hydrogen evolution reaction(HER) electrocatalysts for industrial hydrogen production in the future.
基金supported by the National Natural Science Foundation of China(Grant No.52372283)China Postdoctoral Science Foundation(Grant No.2023M730826)+1 种基金Heilongjiang Postdoctoral Fund(Grant No.LBH-Z23121)Postdoctoral Fellowship Program of CPSF(Grant No.GZC20233425).
文摘Single-atom materials have demonstrated attractive physicochemical characteristics.However,understanding the relationships between the coordination environment of single atoms and their properties at the atomic level remains a considerable challenge.Herein,a facile waterassisted carbonization approach is developed to fabricate well-defined asymmetrically coordinated Co–N_(4)–O sites on biomass-derived carbon nanofiber(Co–N_(4)–O/NCF)for electromagnetic wave(EMW)absorption.In such nanofiber,one atomically dispersed Co site is coordinated with four N atoms in the graphene basal plane and one oxygen atom in the axial direction.In-depth experimental and theoretical studies reveal that the axial Co–O coordination breaks the charge distribution symmetry in the planar porphyrin-like Co–N_(4) structure,leading to significantly enhanced dielectric polarization loss relevant to the planar Co–N_(4) sites.Importantly,the film based on Co–N_(4)–O/NCF exhibits light weight,flexibility,excellent mechanical properties,great thermal insulating feature,and excellent EMW absorption with a reflection loss of−45.82 dB along with an effective absorption bandwidth of 4.8 GHz.The findings of this work offer insight into the relationships between the single-atom coordination environment and the dielectric performance,and the proposed strategy can be extended toward the engineering of asymmetrically coordinated single atoms for various applications.
基金supported by National Natural Science Foundation of China(52373221,U1910208,52250119)the National Key R&D Program of China(2020YFA0710403)the Scientific Research Fund of Hunan Provincial Education Department(NO.23B0114).
文摘Single-atom(SA)catalysts with nearly 100%atom utilization have been widely employed in electrolysis for decades,due to the outperforming catalytic activity and selectivity.However,most of the reported SA catalysts are fixed through the strong bonding between the dispersed single metallic atoms with nonmetallic atoms of the substrates,which greatly limits the controllable regulation of electrocatalytic activity of SA catalysts.In this work,Pt-Ni bonded Pt SA catalyst with adjustable electronic states was successfully constructed through a controllable electrochemical reduction on the coordination unsaturated amorphous Ni(OH)_(2)nanosheet arrays.Based on the X-ray absorption fine structure analysis and first-principles calculations,Pt SA was bonded with Ni sites of amorphous Ni(OH)_(2),rather than conventional O sites,resulting in negatively charged Pt^(δ-).In situ Raman spectroscopy revealed that the changed configuration and electronic states greatly enhanced absorbability for activated hydrogen atoms,which were the essential intermediate for alkaline hydrogen evolution reaction.The hydrogen spillover process was revealed from amorphous Ni(OH)_(2)that effectively cleave the H-O-H bond of H_(2)O and produce H atom to the Pt SA sites,leading to a low overpotential of 48 mV in alkaline electrolyte at-1000 mA cm^(-2)mg^(-1)_(Pt),evidently better than commercial Pt/C catalysts.This work provided new strategy for the control-lable modulation of the local structure of SA catalysts and the systematic regulation of the electronic states.
