The scaling-up of electrochemical CO_(2)reduction requires circumventing the CO_(2)loss as carbonates under alkaline conditions.Zero-gap MEA cell configurations with a proton exchange membrane represent an alternative...The scaling-up of electrochemical CO_(2)reduction requires circumventing the CO_(2)loss as carbonates under alkaline conditions.Zero-gap MEA cell configurations with a proton exchange membrane represent an alternative solution in a pure acidic system,but the catalyst layer in direct contact with the hydrated proton environment usually leads to H_(2)evolution dominating.Herein,we show that polydimethyldiallyl-ammonium-chloride-coated Ag(Ag@PDDA)electrode exhibits outstanding performance with a FE of 86%,a single-pass conversion of 72%,and a stability of 28 h for CO production in pure-acid MEA compared with ammonium poly(N-methyl-piperidine-co-pterphenyl)decorated Ag(Ag/QAPPT)and cetyltrimethylammonium bromide decorated Ag(Ag/CTAB).The in situ ATR-SEIRAS reveal that PDDA creates a positive charge-rich protective outer layer and an N-rich hybrid inner layer,which not only suppresses the migration of H+during the electrolysis process and blocks the direct contact between H2O and Ag catalyst,but also promotes the generation from CO_(2)to*COOH in a pure-acid system.This work highlights the importance of polyelectrolyte engineering in regulating the electrocatalytic interface and accelerates the development of proton exchange membrane CO_(2)electrolysis.展开更多
The hydrogen evolution reaction(HER)is crucial for hydrogen production and sustainable energy storage.Molybdenum disulfide(MoS_(2)),a representative transition metal dichalcogenides(TMDs),shows potential as an HER cat...The hydrogen evolution reaction(HER)is crucial for hydrogen production and sustainable energy storage.Molybdenum disulfide(MoS_(2)),a representative transition metal dichalcogenides(TMDs),shows potential as an HER catalyst but suffers from limited performance due to poor charge transfer and interfacial effects.Here,we report a salt-assisted chemical vapor deposition(CVD)method for synthesizing high-quality tungsten ditelluride(WTe_(2))with tunable morphologies using alkali halides(NaCl,KCl and LiCl).The prepared WTe_(2) nanoribbons and hexagonal nanosheets exhibit morphology-dependent electrical conductivity,with nanosheets showing superior performance.To evaluate WTe_(2) as a contact electrode,WTe_(2)−MoS_(2) heterostructures were fabricated and compared with graphene-MoS_(2) counterparts.The WTe_(2)−MoS_(2) heterostructure exhibits a superior Tafel slope of 111.57 mV/dec and an overpotential of 298 mV at-10 mA/cm^(2),significantly outperforming graphene-based electrodes.This improvement is attributed to the excellent conductivity of WTe_(2) and reduced interfacial Schottky barriers.Moreover,we systematically investigate the influence of WTe_(2) thickness on HER performance and assess the electrochemical durability and structural stability of the heterostructure,further confirming the effectiveness of WTe_(2) as a contact electrode for enhancing the HER activity of MoS_(2).This study offers a novel approach for enhancing the HER performance of MoS_(2) through controlled WTe_(2) growth and application as a contact electrode.Our findings provide valuable insights into the synthesis of high-quality WTe_(2) and broaden the potential applications of two-dimensional materials in energy catalysis.展开更多
Efficient alkaline hydrogen evolution reaction(HER)catalysts are critical for anion exchange membrane water electrolysis(AEMWE).However,the intrinsic scaling relationship between water dissociation and OH desorption f...Efficient alkaline hydrogen evolution reaction(HER)catalysts are critical for anion exchange membrane water electrolysis(AEMWE).However,the intrinsic scaling relationship between water dissociation and OH desorption fundamentally impedes designing catalysts requiring concurrent superior water dissociation and facile OH desorption.Here,we engineer a superhydrophilic Ru/Cr_(2)O_(3) heterostructured electrocatalyst through in situ confinement of Ru nanoparticles(5-10 nm)within a Cr_(2)O_(3) matrix.Acting as a Lewis acid,the Cr_(2)O_(3) component provides alternative sites for water dissociation,accelerating the Volmer step kinetics and downshifting the Ru d-band center via interfacial charge transfer,while simultaneously adsorbing OH-to form a surface-bound Lewis base that repels excess OH-from Ru sites,thereby suppressing hydroxyl over-adsorption.Concurrently,the superhydrophilic surface architecture promotes efficient hydrogen bubble release,thereby reducing mass transport resistance.As a result,the Ru/Cr_(2)O_(3) heterostructured electrocatalyst exhibits an ultralow overpotential of 36.7 mV at 10 mA cm^(-2) and a Tafel slope of 33.2 mV dec^(-1).Integrated into an AEMWE device,the electrode delivers500 mA cm^(-2) for 2000 h in 1.0 M KOH,underscoring its industrial viability(hydrogen production energy consumption per cubic meter(EW):3.94 kW h m^(-3);electricity-to-hydrogen energy conversion efficiency(η_(ETH)):89%@80℃).展开更多
Doping engineering is an effective strategy for graphitic carbon nitride(g-C_(3)N_(4))to improve its photocat-alytic hydrogen evolution reaction(HER)performance.In this work,a novel nitrogen and sulfur co-doped g-C_(3...Doping engineering is an effective strategy for graphitic carbon nitride(g-C_(3)N_(4))to improve its photocat-alytic hydrogen evolution reaction(HER)performance.In this work,a novel nitrogen and sulfur co-doped g-C_(3)N_(4)(N,S-g-C_(3)N_(4))is elaborately designed on the basis of theoretical predictions of first-principle density functional theory(DFT).The calculated Gibbs free energy of adsorbed hydrogen(ΔGH∗)for N,S-g-C_(3)N_(4) at the N-doping active sites is extremely close to zero(0.01 eV).Inspired by the theoretical predictions,the N,S-g-C_(3)N_(4) is successfully fabricated through ammonia-rich pyrolysis synthesis strategy,in which ammonia is in-situ obtained by pyrolyzing melamine.Subsequent characterizations indicate that the N,S-g-C_(3)N_(4) possesses high specific surface area,outstanding light utilization,good hydrophilicity,and efficient carrier transfer efficiency.Consequently,the N,S-g-C_(3)N_(4) displays an extremely high H2 evolution rate of 8269.9μmol g−1 h−1,achieves an apparent quantum efficiency(AQE)of 3.24%,and also possesses outsatnding durability.Theoretical calculations further demonstrate that N and S dopants can not only introduce doping energy level to reduce the band gap,but also induce charge redistribution to facilitate hydrogen adsorption,thus promoting the photocatalytic HER process.Moreover,femtosecond transient absorption(fs-TA)spectroscopy further corroborates the efficient photogenerated carrier transport of N,S-g-C_(3)N_(4).This research highlights a promising and reliable strategy to achieve superior photocatalytic activity,and exhibits significant guidance for precise designing high-efficiency photocatalysts.展开更多
Artificial carbon fixation is a promising pathway for achieving the carbon cycle and environment remediation.However,the sluggish kinetics of oxygen evolution reaction(OER)and poor selectivity of CO_(2) reduction seri...Artificial carbon fixation is a promising pathway for achieving the carbon cycle and environment remediation.However,the sluggish kinetics of oxygen evolution reaction(OER)and poor selectivity of CO_(2) reduction seriously limited the overall conversion efficiencies of solar energy to chemical fuels.Herein,we demonstrated a facile and feasible strategy to rationally regulate the coordination environment and electronic structure of surface-active sites on both photoanode and cathode.More specifically,the defect engineering has been employed to reduce the coordination number of ultrathin FeNi catalysts decorated on BiVO4 photoanodes,resulting in one of the highest OER activities of 6.51 mA cm^(−2)(1.23 VRHE,AM 1.5G).Additionally,single-atom cobalt(II)phthalocyanine anchoring on the N-rich carbon substrates to increase Co–N coordination number remarkably promotes CO_(2) adsorption and activation for high selective CO production.Their integration achieved a record activity of 109.4μmol cm^(−2) h−1 for CO production with a faradaic efficiency of>90%,and an outstanding solar conversion efficiency of 5.41%has been achieved by further integrating a photovoltaic utilizing the sunlight(>500 nm).展开更多
Developing efficient and stable catalysts for the hydrogen evolution reaction(HER)is essential for advancing anion-exchange membrane water electrolyzer(AEMWE)technology.In this study,we present a facile microwave redu...Developing efficient and stable catalysts for the hydrogen evolution reaction(HER)is essential for advancing anion-exchange membrane water electrolyzer(AEMWE)technology.In this study,we present a facile microwave reduction and low-temperature phosphorization strategy to synthesize a highly efficient HER catalyst,comprising P,N-codoped carbon-supported RuP_(2)nanocluster(RuP_(2)@PNC).RuP_(2)@PNC demonstrates outstanding HER performance,achieving overpotentials of 18 and 44 mV at a current density of 10 mA cm^(-2)in alkaline and acidic media,respectively.Furthermore,an AEMWE device utilizing RuP_(2)@PNC as the cathode catalyst delivers a current density of 0.5 A cm^(-2)at a cell voltage of 1.84 V and exhibits remarkable stability over 150 h of operation.Experimental analyses and density functional theory(DFT)calculations reveal that the synergistic effects of P,N-codoped and the unique structure of RuP_(2)enhance electron transfer between Ru and the support,optimize the electronic structure,and regulate the d–band center of Ru.These features improve water adsorption,weaken the Ru–H binding strength,and facilitate efficient H_(2)desorption,collectively driving the superior HER activity of RuP_(2)@PNC.This work offers an effective design strategy for high-performance HER catalysts and provides valuable insights for accelerating the development of AEMWE technology.展开更多
Hydrogen peroxide(H_(2)O_(2)),an environmentally friendly chemical with high value,is extensively used in industrial production and daily life.However,the traditional anthraquinone method for H_(2)O_(2) production is ...Hydrogen peroxide(H_(2)O_(2)),an environmentally friendly chemical with high value,is extensively used in industrial production and daily life.However,the traditional anthraquinone method for H_(2)O_(2) production is associated with a highly energy-consuming and heavily polluting process.Solor-driven photocatalytic evolution of H_(2)O_(2) is a promising,eco-friendly,and energy-efficient strategy that holds great potential to substitute the traditional approach.Here,a ternary photocatalyst,NiS/CdS/Halloysite nanotubes(NiS/CdS/HNTs)is designed and prepared with an earth-abundant clay mineral HNTs as the support and NiS as a co-catalyst.The pivotal roles of HNTs and NiS in the photocatalytic process are elucidated by experiments and theoretical calculations.HNTs serve as the carrier,which allows CdS to be uniformly dispersed onto its surface as small particles,increasing effective contact with H_(2)O and O_(2) for H_(2)O_(2) formation.Simultaneously,it resulted in the formation of a Schottky junction between NiS and CdS,which not only favors photogenerated charges separating efficiently but also provides a unidirectional path to transfer electrons.Consequently,the optimized NiS/CdS/HNTs composite demonstrates an H_(2)O_(2) evolution rate of 380.5μmol·g^(-1)·h^(-1) without adding any sacrificial agent or extra O_(2),nearly 5.0 times that of pure CdS.This work suggests a feasible idea for designing and developing highly active and low-cost solar energy catalytic composite materials.展开更多
Heterojunctions constructed by traditional methods often result in random stacking of materials, leading to lattice mismatch, which adversely affects the extraction and transfer of photo-generated carriers and, in tur...Heterojunctions constructed by traditional methods often result in random stacking of materials, leading to lattice mismatch, which adversely affects the extraction and transfer of photo-generated carriers and, in turn, hampers light utilization efficiency. In this work, we report a novel heterojunction comprising alternating S-doped g-C_(3)N_(4) (SCN) and N-doped MoS_(2) (NMS), bridged by Mo–N covalent bonds within hierarchical periodic macroporous (HPM) walls. This heterojunction is synthesized by co-pyrolyzing dicyandiamide, thiourea, and ammonium molybdate. Transient reflectance photoluminescence measurements reveal that the Mo–N covalent bonds serve as “fast tracks” for electron transfer from SCN to NMS, significantly enhancing the charge separation efficiency. Additionally, the well-defined spatial separation of photo-induced carriers, coupled with the efficient mass transfer within the HPM structure, promotes superior carrier utilization. Thanks to the synergistic effect of HPM structures and the bridged Mo–N bonds, the optimized HPM NMS/SCN-1.3 sample exhibits a remarkable H_(2) evolution rate of 473.3 µmol g^(−1) h^(−1) under visible light irradiation, which is approximately 163 and 19 times higher than bulk g-C_(3)N_(4) (BCN) and HPM SCN, respectively. This work offers valuable insights into the design of HPM heterojunctions composed of co-catalysts and host catalysts, paving the way for enhanced photocatalytic H₂ evolution.展开更多
Lattice-strain engineering has demonstrated its capability to influence the electronic structure and catalytic performance of electrocatalysts.Herein,we present a facile method for inducing thermal strain in cobalt/mo...Lattice-strain engineering has demonstrated its capability to influence the electronic structure and catalytic performance of electrocatalysts.Herein,we present a facile method for inducing thermal strain in cobalt/molybdenum nitride rod-shaped structures(denoted Co/Mo_(2)N)via ammonia-assisted reduction,which effectively modulating the HER performance.The optimized Co/Mo_(2)N-500,characterized by 3%tensile lattice strain,demonstrates exceptional HER activity with lower overpotentials of140 mV and 184 mV at high current density of 1000 mA cm^(-2)in alkaline freshwater and seawater electrolytes,respectively.Co/Mo_(2)N also exhibits excellent long-term durability even at a high current density of 300 mA cm^(-2),surpassing its counterparts and benchmark Pt/C catalyst.Density functional theory calculations validate that the tensile strain optimizes the d-band states,water dissociation,and hydrogen adsorption kinetics of the strained Mo_(2)N in Co/Mo_(2)N,thereby improving its catalytic efficacy.This work provides valuable insights into controlling lattice strain to develop highly efficient electrocatalysts towards advanced electrocatalytic applications.展开更多
NiS2 is a promising cocatalyst to improve the photocatalytic performance of g-C3N4 for the production of H2.However,the synthesis of the NiS2 cocatalyst usually requires harsh conditions,which risks destroying the mic...NiS2 is a promising cocatalyst to improve the photocatalytic performance of g-C3N4 for the production of H2.However,the synthesis of the NiS2 cocatalyst usually requires harsh conditions,which risks destroying the microstructures of the g-C3N4 photocatalysts.In this study,a facile and low-temperature（80 ℃） impregnation method was developed to prepare NiS2/g-C3N4 photocatalysts.First,the g-C3N4 powders were processed by the hydrothermal method in order to introduce oxygen-containing functional groups（such as-OH and-C0NH-） to the surface of g-C3N4.Then,the Ni^2＋ ions could be adsorbed near the g-C3N4 via strong electrostatic interaction between g-C3N4 and Ni^2＋ ions upon the addition of Ni（NO3）2 solution.Finally,NiS2 nanoparticles were formed on the surface of g-C3N4 upon the addition of TAA.It was found that the NiS2 nanoparticles were solidly and homogeneously grafted on the surface of g-C3N4,resulting in greatly improved photocatalytic H2production.When the amount of NiS2 was 3 wt%,the resultant NiS2/g-C3N4 photocatalyst showed the highest H2 evolution rate（116.343 μmol h^-1 g^-1）,which is significantly higher than that of the pure g-C3N4（3 μmol h^-1 g^-1）.Moreover,the results of a recycling test for the NiS2/g-C3N4（3 wt%）sample showed that this sample could maintain a stable and effective photocatalytic H2-evolution performance under visible-light irradiation.Based on the above results,a possible mechanism of the improved photocatalytic performance was proposed for the presented NiS2/g-C3N4 photocatalysts,in which the photogenerated electrons of g-C3N4 can be rapidly transferred to the NiS2 nanoparticles via the close and continuous contact between them;then,the photogenerated electrons rapidly react with H2O adsorbed on the surface of NiS2,which has a surficial metallic character and high catalytic activity,to produce H2.Considering the mild and facile synthesis method,the presented low-cost and highly efficient NiS2-modified g-C3N4 photocatalysts would have great potential for practical use in photocatalytic H2 production.展开更多
Middle-sized chambers (40cmx40cmx20 cm) and an infrared gas analyzer (IRGA) were used for the measurement of net photosynthesis of the grass layer and soil CO2 evolution, in Quercus liaotungensis Koidz. forest, which ...Middle-sized chambers (40cmx40cmx20 cm) and an infrared gas analyzer (IRGA) were used for the measurement of net photosynthesis of the grass layer and soil CO2 evolution, in Quercus liaotungensis Koidz. forest, which is a typical temperate forest ecosystem in the mountainous areas of Beijing. Changes of CO2 concentrations in both the atmosphere (2m above canopy) and the forest canopy (2m below the top of the canopy) together with those of net photosynthesis and soil CO2 evolution were also examined, in order to find the characteristics of CO2 exchange between the different components of the temperate forest ecosystem and the atmosphere. Atmospheric CO2 averaged (323+10) and (330+1) mol mol-1 respectively in summer and autumn. During the 24-hour measurements, large differences as much as -46 and -61 mol mol-1 respectively in the atmosphere and forest were found. Net photosynthesis of the grass layer in summer was (2. 59 9+ 1.05) mol CO2 m-2 S-1, two times of that in autumn, (1.31+0.39) mol CO2 s-1 In summer, there was much more CO2 evolved from soil than in autumn, averaging (5.18+0.75) mol CO2 m-2 s-1 and (1.96 + 0.57) (mol CO2 m-2 s-1, respectively. A significant correlation was found between soil CO2 evolution and ground temperature, with F =-0.864 2+0.310 1X,r=0.7164, P<0.001 (n=117). Both the minimal atmospheric CO2 level and the maximum net photosynthesis occurred around 14:00; and an increase in atmospheric CO2 and of soil CO2 evolution during night times were also found to be remarkable.展开更多
The rapid recombination of photogenerated carriers poses a significant limitation on the use of CdS quantum dots(QDs)in photocatalysis.Herein,the construction of a novel S-scheme heterojunction between cubic-phase CdS...The rapid recombination of photogenerated carriers poses a significant limitation on the use of CdS quantum dots(QDs)in photocatalysis.Herein,the construction of a novel S-scheme heterojunction between cubic-phase CdS QDs and hollow nanotube In_(2)O_(3)is successfully achieved using an electrostatic self-assembly method.Under visible light irradiation,all CdS-In_(2)O_(3)composites exhibit higher hydrogen evolution efficiency compared to pure CdS QDs.Notably,the photocatalytic H_(2)evolution rate of the optimal CdS-7%In_(2)O_(3)composite is determined to be 2258.59μmol g^(−1)h^(−1),approximately 12.3 times higher than that of pure CdS.The cyclic test indicates that the CdS-In_(2)O_(3)composite maintains considerable activity even after 5 cycles,indicating its excellent stability.In situ X-ray photoelectron spectroscopy and density functional theory calculations confirm that carrier migration in CdS-In_(2)O_(3)composites adheres to a typical S-scheme heterojunction mechanism.Additionally,a series of characterizations demonstrate that the formation of S-scheme heterojunctions between In_(2)O_(3)and CdS inhibits charge recombination and accelerates the separation and migration of photogenerated carriers in the CdS QDs,thus achieving enhanced photocatalytic performance.This work elucidates the pivotal role of S-scheme heterojunctions in photocatalytic H_(2)production and offers novel insights into the construction of effective composite photocatalysts.展开更多
Photoreforming poly(lactic acid)(PLA)plastics into pyruvic acid(PA)coupled with hydrogen evolution is of great significance for sustainable development.However,a significant challenge lies inα-OH bond cleaving of lac...Photoreforming poly(lactic acid)(PLA)plastics into pyruvic acid(PA)coupled with hydrogen evolution is of great significance for sustainable development.However,a significant challenge lies inα-OH bond cleaving of lactic acid(LA).Herein,CdS/Bi_(4)Ti_(3)O_(12)composite is fabricated,bridged by Bi−S bonds,through in-situ growth of CdS nanoparticles on Bi_(4)Ti_(3)O_(12)nanoflowers for the successive removal of hydrogen fromα-C in LA.In-situ X-ray photoelectron spectroscopy confirms the S-scheme carriers transfer route and interfacial Bi−S bond in CdS/Bi_(4)Ti_(3)O_(12).Consequently,the photo-electrons and holes with extended lifetimes and strong redox potential accumulate in the CdS conduction band and Bi_(4)Ti_(3)O_(12)valence band,respectively,as evidenced by in-situ electron spin resonance and time-resolved photoluminescence.This facilitates the generation of·OH radicals,which further participate in the successive dehydrogenation reaction of LA.Consequently,the photoreforming efficiencies of converting PLA into PA and H_(2)by CdS/Bi_(4)Ti_(3)O_(12)are 1.7 and 3.16 mmol g^(-1)h^(-1),which are respectively 2.8 and 22 times higher than that by pristine Bi_(4)Ti_(3)O_(12).The present work provides a new approach for designing S-scheme to achieve hydrogen production and value-added conversion of plastics.展开更多
As one of the most important industrially viable methods for carbon dioxide(CO_(2))utilization,methanol synthesis serves as a platform for production of green fuels and commodity chemicals.For sustainable methanol syn...As one of the most important industrially viable methods for carbon dioxide(CO_(2))utilization,methanol synthesis serves as a platform for production of green fuels and commodity chemicals.For sustainable methanol synthesis,In_(2)O_(3)is an ideal catalyst and has garnered significant attention.Herein,cubic In_(2)O_(3)nanoparticles were prepared via the precipitation method and evaluated for CO_(2)hydrogenation to produce methanol.During the initial 10 h of reaction,CO_(2)conversion gradually increased,accompanied by a slow decrease of methanol selectivity,and the reaction reached equilibrium after 10-20 h on stream.This activation and induction stage may be attributed to the sintering of In_(2)O_(3)nanoparticles and the creation of more oxygen vacancies on In_(2)O_(3)surfaces.Further experimental studies demonstrate that hydrogen induction created additional oxygen vacancies during the catalyst activation stage,enhancing the performance of In_(2)O_(3)catalyst for CO_(2)hydrogenation.Density functional theory calculations and microkinetic simulations further demonstrated that surfaces with higher oxygen vacancy coverages or hydroxylated surfaces formed during this induction period can enhance the reaction rate and increase the CO_(2)conversion.However,they predominantly promote the formation of CO instead of methanol,leading to reduced methanol selectivity.These predictions align well with the above-mentioned experimental observations.Our work thus provides an in-depth analysis of the induction stage of the CO_(2)hydrogenation process on In_(2)O_(3)nano-catalyst,and offers valuable insights for significantly improving the CO_(2)reactivity of In_(2)O_(3)-based catalysts while maintaining long-term stability.展开更多
MgO has been shown to facilitate the precipitation of MgO-rich crystalline phases within the MgO-CaO-Al_(2)O_(3)-SiO_(2)(MCAS)glassy inclusion system,which possesses a high liquidus temperature and a significant Young...MgO has been shown to facilitate the precipitation of MgO-rich crystalline phases within the MgO-CaO-Al_(2)O_(3)-SiO_(2)(MCAS)glassy inclusion system,which possesses a high liquidus temperature and a significant Young’s modulus.The underlying linkage between the structural evolution and the crystallization characteristics of the MCAS system was systematically investigated using molecular dynamics simulation and thermodynamic calculation.The results revealed that Mg^(2+) ions played a dual role,constructing networks through the formation of tricluster oxygens while consuming bridging oxygens(BOs)in a mechanism similar to Ca^(2+) ions.However,despite this dual role,the network connectivity was still decreased with the increase in MgO/(MgO+Al_(2)O_(3))(M/(M+A))and CaO/(CaO+SiO_(2))(C/(C+S))ratios,primarily due to the reduction in BOs.This microscopic structural evolution resulted in a reduction in viscosity and an enhancement of crystallization ability.Furthermore,the remarkable diffusion capability of Mg^(2+) ions,coupled with the increased proportion of 6-coordinated Mg^(2+)ions,unveiled the mechanism underlying the precipitation of MgSiO_(3) and Mg_(2)SiO_(4) crystals,which exhibited high Young’s moduli of 165.23 and 196.67 GPa,respectively.To prevent the precipitation of MgO-rich crystalline phases,it was crucial to maintain the M/(M+A)ratio below 0.42 and the C/(C+S)ratio below 0.16 within the MCAS system.展开更多
Underground carbon sequestration(CS)by solid waste backfill(SWB)offers an effective pathway for collaborative disposal of coal-based solid waste and CO_(2),where the amount of carbon sequestration is an important eval...Underground carbon sequestration(CS)by solid waste backfill(SWB)offers an effective pathway for collaborative disposal of coal-based solid waste and CO_(2),where the amount of carbon sequestration is an important evaluation parameter.In this study,the concept of whole-process carbon sequestration using coal-based solid waste and CO_(2),including sequential stirring and curing stages,was proposed to evaluate the performance evolution of CS.The results showed that CO_(2) pressure and ambient temperature positively correlated with the CS amount from coal-based SWB.In particular,CO_(2) pressure prevailed in the stirring stage,while the ambient temperature effect was more significant in the curing stage.The CS amounts obtained during the stirring stage alone,the curing stage alone,and two sequential stages ranged from 0.66%–3.10%,3.53%–5.09%,and 5.12%–6.02%,respectively.The functional group and micromorphology analyses revealed that the prevailing mechanism at the CS stirring stage was the stirringdriven gas dissolution-leaching-mineralization reaction,while that at the curing stage was the hydration-driven gas permeation-dissociation-CS reaction.Both were essentially solid-liquid-gas multiphase chemical reactions.The results are instrumental in substantiating the coal-based SWB carbon sequestration evolution patterns and mechanisms and providing data support for waste disposal and carbon emission reduction in the coal industry.展开更多
Small-sized Cd_(x) Zn_(1-x) S solid solution nanomaterial is an important candidate for efficient photocatalytic hydrogen evolution(PHE),but it still suffers from easy agglomeration,severe photo corrosion,and fast pho...Small-sized Cd_(x) Zn_(1-x) S solid solution nanomaterial is an important candidate for efficient photocatalytic hydrogen evolution(PHE),but it still suffers from easy agglomeration,severe photo corrosion,and fast photogenerated electron-hole recombination.To tackle these issues,herein,we propose a new strategy to modify Cd_(x) Zn_(1-x) S nanoreactors by the simultaneous utilization of ionic-liquid-assisted morphology engineering and MXene-incorporating method.That is,we designed and synthesized a novel hierarchi-cal Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) Schottky junction composite through the in-situ deposition of ultrathin Cd_(0.8) Zn_(0.2) S nanosheets on unique IL-modified Ti_(3) C_(2) MXenes by a one-pot solvothermal method for efficiently PHE.The unique construction strategy tailors the thickness of ultrathin Cd_(0.8) Zn_(0.2) S nanosheets and prevents them from stacking and agglomeration,and especially,optimizes their charge transfer pathways during the photocatalytic process.Compared with pristine Cd_(0.8) Zn_(0.2) S nanosheets,Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) has abun-dant photogenerated electrons available on the Ti_(3) C_(2) surface for proton reduction reaction,owing to the absence of deep-trapped electrons,suppression of electron-hole recombination in Cd_(0.8) Zn_(0.2) S and high-efficiency charge separation at the Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) Schottky junction interface.Moreover,the hy-drophilicity,electrical conductivity,visible-light absorption capacity,and surficial hydrogen desorption of Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) heterostructure are significantly improved.As a result,the heterostructure exhibits out-standing photocatalytic stability and super high apparent quantum efficiency,being rendered as one of the best noble-metal-free Cd-Zn-S-based photocatalysts.This work illustrates the mechanisms of mor-phology control and heterojunction construction in controlling the catalytic behavior of photocatalysts and highlights the great potential of the IL-assisted route in the synthesis of high-performance MXene-based heterostructures for photocatalytic hydrogen evolution.展开更多
基金financial support of the National Natural Science Foundation of China(NSFC)(52394202,52021004,52301232,and 52476056)the Natural Science Foundation of Chongqing Province(2024NSCQ-MSX1109).
文摘The scaling-up of electrochemical CO_(2)reduction requires circumventing the CO_(2)loss as carbonates under alkaline conditions.Zero-gap MEA cell configurations with a proton exchange membrane represent an alternative solution in a pure acidic system,but the catalyst layer in direct contact with the hydrated proton environment usually leads to H_(2)evolution dominating.Herein,we show that polydimethyldiallyl-ammonium-chloride-coated Ag(Ag@PDDA)electrode exhibits outstanding performance with a FE of 86%,a single-pass conversion of 72%,and a stability of 28 h for CO production in pure-acid MEA compared with ammonium poly(N-methyl-piperidine-co-pterphenyl)decorated Ag(Ag/QAPPT)and cetyltrimethylammonium bromide decorated Ag(Ag/CTAB).The in situ ATR-SEIRAS reveal that PDDA creates a positive charge-rich protective outer layer and an N-rich hybrid inner layer,which not only suppresses the migration of H+during the electrolysis process and blocks the direct contact between H2O and Ag catalyst,but also promotes the generation from CO_(2)to*COOH in a pure-acid system.This work highlights the importance of polyelectrolyte engineering in regulating the electrocatalytic interface and accelerates the development of proton exchange membrane CO_(2)electrolysis.
基金support from the National Natural Science Foundation of China(No.22175060).
文摘The hydrogen evolution reaction(HER)is crucial for hydrogen production and sustainable energy storage.Molybdenum disulfide(MoS_(2)),a representative transition metal dichalcogenides(TMDs),shows potential as an HER catalyst but suffers from limited performance due to poor charge transfer and interfacial effects.Here,we report a salt-assisted chemical vapor deposition(CVD)method for synthesizing high-quality tungsten ditelluride(WTe_(2))with tunable morphologies using alkali halides(NaCl,KCl and LiCl).The prepared WTe_(2) nanoribbons and hexagonal nanosheets exhibit morphology-dependent electrical conductivity,with nanosheets showing superior performance.To evaluate WTe_(2) as a contact electrode,WTe_(2)−MoS_(2) heterostructures were fabricated and compared with graphene-MoS_(2) counterparts.The WTe_(2)−MoS_(2) heterostructure exhibits a superior Tafel slope of 111.57 mV/dec and an overpotential of 298 mV at-10 mA/cm^(2),significantly outperforming graphene-based electrodes.This improvement is attributed to the excellent conductivity of WTe_(2) and reduced interfacial Schottky barriers.Moreover,we systematically investigate the influence of WTe_(2) thickness on HER performance and assess the electrochemical durability and structural stability of the heterostructure,further confirming the effectiveness of WTe_(2) as a contact electrode for enhancing the HER activity of MoS_(2).This study offers a novel approach for enhancing the HER performance of MoS_(2) through controlled WTe_(2) growth and application as a contact electrode.Our findings provide valuable insights into the synthesis of high-quality WTe_(2) and broaden the potential applications of two-dimensional materials in energy catalysis.
基金supported by the National Natural Science Foundation of China(22479113,52101268)the Fundamental Research Funds for the Central Universities(buctrc202323)。
文摘Efficient alkaline hydrogen evolution reaction(HER)catalysts are critical for anion exchange membrane water electrolysis(AEMWE).However,the intrinsic scaling relationship between water dissociation and OH desorption fundamentally impedes designing catalysts requiring concurrent superior water dissociation and facile OH desorption.Here,we engineer a superhydrophilic Ru/Cr_(2)O_(3) heterostructured electrocatalyst through in situ confinement of Ru nanoparticles(5-10 nm)within a Cr_(2)O_(3) matrix.Acting as a Lewis acid,the Cr_(2)O_(3) component provides alternative sites for water dissociation,accelerating the Volmer step kinetics and downshifting the Ru d-band center via interfacial charge transfer,while simultaneously adsorbing OH-to form a surface-bound Lewis base that repels excess OH-from Ru sites,thereby suppressing hydroxyl over-adsorption.Concurrently,the superhydrophilic surface architecture promotes efficient hydrogen bubble release,thereby reducing mass transport resistance.As a result,the Ru/Cr_(2)O_(3) heterostructured electrocatalyst exhibits an ultralow overpotential of 36.7 mV at 10 mA cm^(-2) and a Tafel slope of 33.2 mV dec^(-1).Integrated into an AEMWE device,the electrode delivers500 mA cm^(-2) for 2000 h in 1.0 M KOH,underscoring its industrial viability(hydrogen production energy consumption per cubic meter(EW):3.94 kW h m^(-3);electricity-to-hydrogen energy conversion efficiency(η_(ETH)):89%@80℃).
基金supported by the National Natural Science Foun-dation of China(No.62004143)the Key R&D Program of Hubei Province(No.2022BAA084)the Natural Science Foundation of Hubei Province(No.2021CFB133).
文摘Doping engineering is an effective strategy for graphitic carbon nitride(g-C_(3)N_(4))to improve its photocat-alytic hydrogen evolution reaction(HER)performance.In this work,a novel nitrogen and sulfur co-doped g-C_(3)N_(4)(N,S-g-C_(3)N_(4))is elaborately designed on the basis of theoretical predictions of first-principle density functional theory(DFT).The calculated Gibbs free energy of adsorbed hydrogen(ΔGH∗)for N,S-g-C_(3)N_(4) at the N-doping active sites is extremely close to zero(0.01 eV).Inspired by the theoretical predictions,the N,S-g-C_(3)N_(4) is successfully fabricated through ammonia-rich pyrolysis synthesis strategy,in which ammonia is in-situ obtained by pyrolyzing melamine.Subsequent characterizations indicate that the N,S-g-C_(3)N_(4) possesses high specific surface area,outstanding light utilization,good hydrophilicity,and efficient carrier transfer efficiency.Consequently,the N,S-g-C_(3)N_(4) displays an extremely high H2 evolution rate of 8269.9μmol g−1 h−1,achieves an apparent quantum efficiency(AQE)of 3.24%,and also possesses outsatnding durability.Theoretical calculations further demonstrate that N and S dopants can not only introduce doping energy level to reduce the band gap,but also induce charge redistribution to facilitate hydrogen adsorption,thus promoting the photocatalytic HER process.Moreover,femtosecond transient absorption(fs-TA)spectroscopy further corroborates the efficient photogenerated carrier transport of N,S-g-C_(3)N_(4).This research highlights a promising and reliable strategy to achieve superior photocatalytic activity,and exhibits significant guidance for precise designing high-efficiency photocatalysts.
基金supported by the National Natural Science Foundation of China(21832005,22072168,22002175)Major Program of the Lanzhou Institute of Chemical Physics,CAS(No.ZYFZFX-3)+1 种基金Major Science and Technology Projects in Gansu Province(22ZD6GA003)West Light Foundation of The Chinese Academy of Sciences(xbzg-zdsys-202209).
文摘Artificial carbon fixation is a promising pathway for achieving the carbon cycle and environment remediation.However,the sluggish kinetics of oxygen evolution reaction(OER)and poor selectivity of CO_(2) reduction seriously limited the overall conversion efficiencies of solar energy to chemical fuels.Herein,we demonstrated a facile and feasible strategy to rationally regulate the coordination environment and electronic structure of surface-active sites on both photoanode and cathode.More specifically,the defect engineering has been employed to reduce the coordination number of ultrathin FeNi catalysts decorated on BiVO4 photoanodes,resulting in one of the highest OER activities of 6.51 mA cm^(−2)(1.23 VRHE,AM 1.5G).Additionally,single-atom cobalt(II)phthalocyanine anchoring on the N-rich carbon substrates to increase Co–N coordination number remarkably promotes CO_(2) adsorption and activation for high selective CO production.Their integration achieved a record activity of 109.4μmol cm^(−2) h−1 for CO production with a faradaic efficiency of>90%,and an outstanding solar conversion efficiency of 5.41%has been achieved by further integrating a photovoltaic utilizing the sunlight(>500 nm).
基金supported by the National Natural Science Foundation of China(Nos.52371222 and 52271211)the Natural Science Foundation of Hunan Province in China(Nos.2025JJ60350,2024JJ4022,and 2023JJ30277)+1 种基金the Key Research and Development Program of Hunan Province(No.2023GK2035)HORIZON–Marie Sk?odowska–Curie Actions–2021–PF(No.101065098),European Union
文摘Developing efficient and stable catalysts for the hydrogen evolution reaction(HER)is essential for advancing anion-exchange membrane water electrolyzer(AEMWE)technology.In this study,we present a facile microwave reduction and low-temperature phosphorization strategy to synthesize a highly efficient HER catalyst,comprising P,N-codoped carbon-supported RuP_(2)nanocluster(RuP_(2)@PNC).RuP_(2)@PNC demonstrates outstanding HER performance,achieving overpotentials of 18 and 44 mV at a current density of 10 mA cm^(-2)in alkaline and acidic media,respectively.Furthermore,an AEMWE device utilizing RuP_(2)@PNC as the cathode catalyst delivers a current density of 0.5 A cm^(-2)at a cell voltage of 1.84 V and exhibits remarkable stability over 150 h of operation.Experimental analyses and density functional theory(DFT)calculations reveal that the synergistic effects of P,N-codoped and the unique structure of RuP_(2)enhance electron transfer between Ru and the support,optimize the electronic structure,and regulate the d–band center of Ru.These features improve water adsorption,weaken the Ru–H binding strength,and facilitate efficient H_(2)desorption,collectively driving the superior HER activity of RuP_(2)@PNC.This work offers an effective design strategy for high-performance HER catalysts and provides valuable insights for accelerating the development of AEMWE technology.
文摘Hydrogen peroxide(H_(2)O_(2)),an environmentally friendly chemical with high value,is extensively used in industrial production and daily life.However,the traditional anthraquinone method for H_(2)O_(2) production is associated with a highly energy-consuming and heavily polluting process.Solor-driven photocatalytic evolution of H_(2)O_(2) is a promising,eco-friendly,and energy-efficient strategy that holds great potential to substitute the traditional approach.Here,a ternary photocatalyst,NiS/CdS/Halloysite nanotubes(NiS/CdS/HNTs)is designed and prepared with an earth-abundant clay mineral HNTs as the support and NiS as a co-catalyst.The pivotal roles of HNTs and NiS in the photocatalytic process are elucidated by experiments and theoretical calculations.HNTs serve as the carrier,which allows CdS to be uniformly dispersed onto its surface as small particles,increasing effective contact with H_(2)O and O_(2) for H_(2)O_(2) formation.Simultaneously,it resulted in the formation of a Schottky junction between NiS and CdS,which not only favors photogenerated charges separating efficiently but also provides a unidirectional path to transfer electrons.Consequently,the optimized NiS/CdS/HNTs composite demonstrates an H_(2)O_(2) evolution rate of 380.5μmol·g^(-1)·h^(-1) without adding any sacrificial agent or extra O_(2),nearly 5.0 times that of pure CdS.This work suggests a feasible idea for designing and developing highly active and low-cost solar energy catalytic composite materials.
基金support of the National Natural Science Foundation of China(Nos.52174238,22378103,52204307,and 22409128)Natural Science Foundation of Changsha(No.kq2208425)the Research Foundation Bureau of Hunan Province(No.24B0787).
文摘Heterojunctions constructed by traditional methods often result in random stacking of materials, leading to lattice mismatch, which adversely affects the extraction and transfer of photo-generated carriers and, in turn, hampers light utilization efficiency. In this work, we report a novel heterojunction comprising alternating S-doped g-C_(3)N_(4) (SCN) and N-doped MoS_(2) (NMS), bridged by Mo–N covalent bonds within hierarchical periodic macroporous (HPM) walls. This heterojunction is synthesized by co-pyrolyzing dicyandiamide, thiourea, and ammonium molybdate. Transient reflectance photoluminescence measurements reveal that the Mo–N covalent bonds serve as “fast tracks” for electron transfer from SCN to NMS, significantly enhancing the charge separation efficiency. Additionally, the well-defined spatial separation of photo-induced carriers, coupled with the efficient mass transfer within the HPM structure, promotes superior carrier utilization. Thanks to the synergistic effect of HPM structures and the bridged Mo–N bonds, the optimized HPM NMS/SCN-1.3 sample exhibits a remarkable H_(2) evolution rate of 473.3 µmol g^(−1) h^(−1) under visible light irradiation, which is approximately 163 and 19 times higher than bulk g-C_(3)N_(4) (BCN) and HPM SCN, respectively. This work offers valuable insights into the design of HPM heterojunctions composed of co-catalysts and host catalysts, paving the way for enhanced photocatalytic H₂ evolution.
基金supported by the Hunan Joint International Laboratory of Advanced Materials and Technology for Clean Energy(2020CB1007)Fundamental Research Funds for the Central Universities and Guangxi Key Laboratory of Information Materials and Guilin University of Electronic Technology,China(231002-K)+4 种基金Natural Science Foundation of Guangxi Zhuang Autonomous Region(2022GXNSFAA035467)Guangxi Science and Technology Program(Guike AD21220067)National Natural Science Foundation of China(22369002)Nationally Funded Postdoctoral Researcher Program(GZC20230756)China Postdoctoral Science Foundation(2024M750858)。
文摘Lattice-strain engineering has demonstrated its capability to influence the electronic structure and catalytic performance of electrocatalysts.Herein,we present a facile method for inducing thermal strain in cobalt/molybdenum nitride rod-shaped structures(denoted Co/Mo_(2)N)via ammonia-assisted reduction,which effectively modulating the HER performance.The optimized Co/Mo_(2)N-500,characterized by 3%tensile lattice strain,demonstrates exceptional HER activity with lower overpotentials of140 mV and 184 mV at high current density of 1000 mA cm^(-2)in alkaline freshwater and seawater electrolytes,respectively.Co/Mo_(2)N also exhibits excellent long-term durability even at a high current density of 300 mA cm^(-2),surpassing its counterparts and benchmark Pt/C catalyst.Density functional theory calculations validate that the tensile strain optimizes the d-band states,water dissociation,and hydrogen adsorption kinetics of the strained Mo_(2)N in Co/Mo_(2)N,thereby improving its catalytic efficacy.This work provides valuable insights into controlling lattice strain to develop highly efficient electrocatalysts towards advanced electrocatalytic applications.
基金supported by the National Natural Science Foundation of China (21277107, 21477094, 51672203, 51472192)the Program for New Century Excellent Talents in University (NCET-13-0944)the Fundamental Research Funds for the Central Universities (WUT 2015IB002)~~
文摘NiS2 is a promising cocatalyst to improve the photocatalytic performance of g-C3N4 for the production of H2.However,the synthesis of the NiS2 cocatalyst usually requires harsh conditions,which risks destroying the microstructures of the g-C3N4 photocatalysts.In this study,a facile and low-temperature（80 ℃） impregnation method was developed to prepare NiS2/g-C3N4 photocatalysts.First,the g-C3N4 powders were processed by the hydrothermal method in order to introduce oxygen-containing functional groups（such as-OH and-C0NH-） to the surface of g-C3N4.Then,the Ni^2＋ ions could be adsorbed near the g-C3N4 via strong electrostatic interaction between g-C3N4 and Ni^2＋ ions upon the addition of Ni（NO3）2 solution.Finally,NiS2 nanoparticles were formed on the surface of g-C3N4 upon the addition of TAA.It was found that the NiS2 nanoparticles were solidly and homogeneously grafted on the surface of g-C3N4,resulting in greatly improved photocatalytic H2production.When the amount of NiS2 was 3 wt%,the resultant NiS2/g-C3N4 photocatalyst showed the highest H2 evolution rate（116.343 μmol h^-1 g^-1）,which is significantly higher than that of the pure g-C3N4（3 μmol h^-1 g^-1）.Moreover,the results of a recycling test for the NiS2/g-C3N4（3 wt%）sample showed that this sample could maintain a stable and effective photocatalytic H2-evolution performance under visible-light irradiation.Based on the above results,a possible mechanism of the improved photocatalytic performance was proposed for the presented NiS2/g-C3N4 photocatalysts,in which the photogenerated electrons of g-C3N4 can be rapidly transferred to the NiS2 nanoparticles via the close and continuous contact between them;then,the photogenerated electrons rapidly react with H2O adsorbed on the surface of NiS2,which has a surficial metallic character and high catalytic activity,to produce H2.Considering the mild and facile synthesis method,the presented low-cost and highly efficient NiS2-modified g-C3N4 photocatalysts would have great potential for practical use in photocatalytic H2 production.
基金This is a key project of National Natural Science Foundation of China.
文摘Middle-sized chambers (40cmx40cmx20 cm) and an infrared gas analyzer (IRGA) were used for the measurement of net photosynthesis of the grass layer and soil CO2 evolution, in Quercus liaotungensis Koidz. forest, which is a typical temperate forest ecosystem in the mountainous areas of Beijing. Changes of CO2 concentrations in both the atmosphere (2m above canopy) and the forest canopy (2m below the top of the canopy) together with those of net photosynthesis and soil CO2 evolution were also examined, in order to find the characteristics of CO2 exchange between the different components of the temperate forest ecosystem and the atmosphere. Atmospheric CO2 averaged (323+10) and (330+1) mol mol-1 respectively in summer and autumn. During the 24-hour measurements, large differences as much as -46 and -61 mol mol-1 respectively in the atmosphere and forest were found. Net photosynthesis of the grass layer in summer was (2. 59 9+ 1.05) mol CO2 m-2 S-1, two times of that in autumn, (1.31+0.39) mol CO2 s-1 In summer, there was much more CO2 evolved from soil than in autumn, averaging (5.18+0.75) mol CO2 m-2 s-1 and (1.96 + 0.57) (mol CO2 m-2 s-1, respectively. A significant correlation was found between soil CO2 evolution and ground temperature, with F =-0.864 2+0.310 1X,r=0.7164, P<0.001 (n=117). Both the minimal atmospheric CO2 level and the maximum net photosynthesis occurred around 14:00; and an increase in atmospheric CO2 and of soil CO2 evolution during night times were also found to be remarkable.
文摘The rapid recombination of photogenerated carriers poses a significant limitation on the use of CdS quantum dots(QDs)in photocatalysis.Herein,the construction of a novel S-scheme heterojunction between cubic-phase CdS QDs and hollow nanotube In_(2)O_(3)is successfully achieved using an electrostatic self-assembly method.Under visible light irradiation,all CdS-In_(2)O_(3)composites exhibit higher hydrogen evolution efficiency compared to pure CdS QDs.Notably,the photocatalytic H_(2)evolution rate of the optimal CdS-7%In_(2)O_(3)composite is determined to be 2258.59μmol g^(−1)h^(−1),approximately 12.3 times higher than that of pure CdS.The cyclic test indicates that the CdS-In_(2)O_(3)composite maintains considerable activity even after 5 cycles,indicating its excellent stability.In situ X-ray photoelectron spectroscopy and density functional theory calculations confirm that carrier migration in CdS-In_(2)O_(3)composites adheres to a typical S-scheme heterojunction mechanism.Additionally,a series of characterizations demonstrate that the formation of S-scheme heterojunctions between In_(2)O_(3)and CdS inhibits charge recombination and accelerates the separation and migration of photogenerated carriers in the CdS QDs,thus achieving enhanced photocatalytic performance.This work elucidates the pivotal role of S-scheme heterojunctions in photocatalytic H_(2)production and offers novel insights into the construction of effective composite photocatalysts.
基金supported by the National Natural Science Foundation of China(Nos.52161145409,21976116)SAFEA of China("Belt and Road"Innovative Talent Exchange Foreign Expert Project No.2023041004L)+1 种基金(High-end Foreign Expert Project No.G2023041021L)Alexander-von-Humboldt Foundation of Germany(Group-Linkage Program).
文摘Photoreforming poly(lactic acid)(PLA)plastics into pyruvic acid(PA)coupled with hydrogen evolution is of great significance for sustainable development.However,a significant challenge lies inα-OH bond cleaving of lactic acid(LA).Herein,CdS/Bi_(4)Ti_(3)O_(12)composite is fabricated,bridged by Bi−S bonds,through in-situ growth of CdS nanoparticles on Bi_(4)Ti_(3)O_(12)nanoflowers for the successive removal of hydrogen fromα-C in LA.In-situ X-ray photoelectron spectroscopy confirms the S-scheme carriers transfer route and interfacial Bi−S bond in CdS/Bi_(4)Ti_(3)O_(12).Consequently,the photo-electrons and holes with extended lifetimes and strong redox potential accumulate in the CdS conduction band and Bi_(4)Ti_(3)O_(12)valence band,respectively,as evidenced by in-situ electron spin resonance and time-resolved photoluminescence.This facilitates the generation of·OH radicals,which further participate in the successive dehydrogenation reaction of LA.Consequently,the photoreforming efficiencies of converting PLA into PA and H_(2)by CdS/Bi_(4)Ti_(3)O_(12)are 1.7 and 3.16 mmol g^(-1)h^(-1),which are respectively 2.8 and 22 times higher than that by pristine Bi_(4)Ti_(3)O_(12).The present work provides a new approach for designing S-scheme to achieve hydrogen production and value-added conversion of plastics.
文摘As one of the most important industrially viable methods for carbon dioxide(CO_(2))utilization,methanol synthesis serves as a platform for production of green fuels and commodity chemicals.For sustainable methanol synthesis,In_(2)O_(3)is an ideal catalyst and has garnered significant attention.Herein,cubic In_(2)O_(3)nanoparticles were prepared via the precipitation method and evaluated for CO_(2)hydrogenation to produce methanol.During the initial 10 h of reaction,CO_(2)conversion gradually increased,accompanied by a slow decrease of methanol selectivity,and the reaction reached equilibrium after 10-20 h on stream.This activation and induction stage may be attributed to the sintering of In_(2)O_(3)nanoparticles and the creation of more oxygen vacancies on In_(2)O_(3)surfaces.Further experimental studies demonstrate that hydrogen induction created additional oxygen vacancies during the catalyst activation stage,enhancing the performance of In_(2)O_(3)catalyst for CO_(2)hydrogenation.Density functional theory calculations and microkinetic simulations further demonstrated that surfaces with higher oxygen vacancy coverages or hydroxylated surfaces formed during this induction period can enhance the reaction rate and increase the CO_(2)conversion.However,they predominantly promote the formation of CO instead of methanol,leading to reduced methanol selectivity.These predictions align well with the above-mentioned experimental observations.Our work thus provides an in-depth analysis of the induction stage of the CO_(2)hydrogenation process on In_(2)O_(3)nano-catalyst,and offers valuable insights for significantly improving the CO_(2)reactivity of In_(2)O_(3)-based catalysts while maintaining long-term stability.
基金support from the National Key R&D Program of China(Grant Nos.2023YFB3709900 and 2023YFB3709903)the National Natural Science Foundation of China(Grant Nos.52174293 and U22A20171)+1 种基金the High Steel Center(HSC)at North China University of TechnologyUniversity of Science and Technology Beijing(USTB).
文摘MgO has been shown to facilitate the precipitation of MgO-rich crystalline phases within the MgO-CaO-Al_(2)O_(3)-SiO_(2)(MCAS)glassy inclusion system,which possesses a high liquidus temperature and a significant Young’s modulus.The underlying linkage between the structural evolution and the crystallization characteristics of the MCAS system was systematically investigated using molecular dynamics simulation and thermodynamic calculation.The results revealed that Mg^(2+) ions played a dual role,constructing networks through the formation of tricluster oxygens while consuming bridging oxygens(BOs)in a mechanism similar to Ca^(2+) ions.However,despite this dual role,the network connectivity was still decreased with the increase in MgO/(MgO+Al_(2)O_(3))(M/(M+A))and CaO/(CaO+SiO_(2))(C/(C+S))ratios,primarily due to the reduction in BOs.This microscopic structural evolution resulted in a reduction in viscosity and an enhancement of crystallization ability.Furthermore,the remarkable diffusion capability of Mg^(2+) ions,coupled with the increased proportion of 6-coordinated Mg^(2+)ions,unveiled the mechanism underlying the precipitation of MgSiO_(3) and Mg_(2)SiO_(4) crystals,which exhibited high Young’s moduli of 165.23 and 196.67 GPa,respectively.To prevent the precipitation of MgO-rich crystalline phases,it was crucial to maintain the M/(M+A)ratio below 0.42 and the C/(C+S)ratio below 0.16 within the MCAS system.
基金supported by the National Key R&D Program of China(No.2023YFC3904304)the National Natural Science Foundation of China(No.52304158)Jiangsu Key Laboratory for Clean Utilization of Carbon Resources Research Project(No.BM2024007)。
文摘Underground carbon sequestration(CS)by solid waste backfill(SWB)offers an effective pathway for collaborative disposal of coal-based solid waste and CO_(2),where the amount of carbon sequestration is an important evaluation parameter.In this study,the concept of whole-process carbon sequestration using coal-based solid waste and CO_(2),including sequential stirring and curing stages,was proposed to evaluate the performance evolution of CS.The results showed that CO_(2) pressure and ambient temperature positively correlated with the CS amount from coal-based SWB.In particular,CO_(2) pressure prevailed in the stirring stage,while the ambient temperature effect was more significant in the curing stage.The CS amounts obtained during the stirring stage alone,the curing stage alone,and two sequential stages ranged from 0.66%–3.10%,3.53%–5.09%,and 5.12%–6.02%,respectively.The functional group and micromorphology analyses revealed that the prevailing mechanism at the CS stirring stage was the stirringdriven gas dissolution-leaching-mineralization reaction,while that at the curing stage was the hydration-driven gas permeation-dissociation-CS reaction.Both were essentially solid-liquid-gas multiphase chemical reactions.The results are instrumental in substantiating the coal-based SWB carbon sequestration evolution patterns and mechanisms and providing data support for waste disposal and carbon emission reduction in the coal industry.
基金financial supports pro-vided by the National Natural Science Foundation of China(No.21905279)the Natural Science Foundation of Fujian Province(No.2020J05086).
文摘Small-sized Cd_(x) Zn_(1-x) S solid solution nanomaterial is an important candidate for efficient photocatalytic hydrogen evolution(PHE),but it still suffers from easy agglomeration,severe photo corrosion,and fast photogenerated electron-hole recombination.To tackle these issues,herein,we propose a new strategy to modify Cd_(x) Zn_(1-x) S nanoreactors by the simultaneous utilization of ionic-liquid-assisted morphology engineering and MXene-incorporating method.That is,we designed and synthesized a novel hierarchi-cal Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) Schottky junction composite through the in-situ deposition of ultrathin Cd_(0.8) Zn_(0.2) S nanosheets on unique IL-modified Ti_(3) C_(2) MXenes by a one-pot solvothermal method for efficiently PHE.The unique construction strategy tailors the thickness of ultrathin Cd_(0.8) Zn_(0.2) S nanosheets and prevents them from stacking and agglomeration,and especially,optimizes their charge transfer pathways during the photocatalytic process.Compared with pristine Cd_(0.8) Zn_(0.2) S nanosheets,Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) has abun-dant photogenerated electrons available on the Ti_(3) C_(2) surface for proton reduction reaction,owing to the absence of deep-trapped electrons,suppression of electron-hole recombination in Cd_(0.8) Zn_(0.2) S and high-efficiency charge separation at the Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) Schottky junction interface.Moreover,the hy-drophilicity,electrical conductivity,visible-light absorption capacity,and surficial hydrogen desorption of Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) heterostructure are significantly improved.As a result,the heterostructure exhibits out-standing photocatalytic stability and super high apparent quantum efficiency,being rendered as one of the best noble-metal-free Cd-Zn-S-based photocatalysts.This work illustrates the mechanisms of mor-phology control and heterojunction construction in controlling the catalytic behavior of photocatalysts and highlights the great potential of the IL-assisted route in the synthesis of high-performance MXene-based heterostructures for photocatalytic hydrogen evolution.
