The hydrogen reduction of tungsten oxides WO_(272)and WO_2 were studied directly using high-temperature X-ray diffraction analysis,The pure β-W was obtained from the reduction of WO_(272)The transformation of β-W to...The hydrogen reduction of tungsten oxides WO_(272)and WO_2 were studied directly using high-temperature X-ray diffraction analysis,The pure β-W was obtained from the reduction of WO_(272)The transformation of β-W to x-W was also studied in both hydrogen and nitrogen.The forming condition of β-W from WO_2 was discussed.Finally.a complete schematic diagram of reduction of tungsten oxides was given in this paper.展开更多
Constructing highly-efficient electrocatalysts toward hydrogen evolution reaction(HER)/oxygen evolution reaction(OER)/oxygen reduction reaction(ORR)with excellent stability is quite important for the development of re...Constructing highly-efficient electrocatalysts toward hydrogen evolution reaction(HER)/oxygen evolution reaction(OER)/oxygen reduction reaction(ORR)with excellent stability is quite important for the development of renewable energy-related applications.Herein,Co-Ru based compounds supported on nitrogen doped two-dimensional(2D)carbon nanosheets(NCN)are developed via one step pyrolysis procedure(Co-Ru/NCN)for HER/ORR and following low-temperature oxidation process(Co-Ru@RuO_(x)/NCN)for OER.The specific 2D morphology guarantees abundant active sites exposure.Furthermore,the synergistic effects arising from the interaction between Co and Ru are crucial in enhancing the catalytic performance.Thus,the resulting Co-Ru/NCN shows remarkable electrocatalytic performance for HER(70 mV at 10 mA cm^(-2))in 1 M KOH and ORR(half-wave potential E_(1/2)=0.81 V)in 0.1 M KOH.Especially,the Co-Ru@RuO_(x)/NCN obtained by oxidation exhibits splendid OER performance in both acid(230 mV at 10 mA cm^(-2))and alkaline media(270 mV at 10 mA cm^(-2))coupled with excellent stability.Consequently,the fabricated two-electrode water-splitting device exhibits excellent performance in both acidic and alkaline environments.This research provides a promising avenue for the advancement of multifunctional nanomaterials.展开更多
Solution-phase hydrogen reduction(Sp HR)was introduced into V_(2)O_(3)preparation to overcome disadvantages of traditional reduction roasting,which include a long process,high energy consumption,and generation of poll...Solution-phase hydrogen reduction(Sp HR)was introduced into V_(2)O_(3)preparation to overcome disadvantages of traditional reduction roasting,which include a long process,high energy consumption,and generation of pollution.The research mainly focuses onφ-pH diagrams and kinetics of SpHR.Thermodynamic analysis ofφ-pH diagrams for the V-H_(2)O system demonstrates that V_(2)O_(3)preparation via Sp HR requires a high temperature,a high vanadium concentration,and sufficient hydrogen in acidic solution.Kinetic analyses show that the activation energy of V_(2)O_(3)preparation via SpHR is 38.0679 k J/mol,indicating that the reduction is controlled by a combination of interfacial chemical reaction and internal diffusion.Effects of H;partial pressure(slope K=0.05246)on the reaction rate is not as significant as the vanadium concentration(K=1.58872).V_(2)O_(3)crystals with a purity of 99.59%and a vanadium precipitation rate of 99.83%were obtained under the following conditions:pH=5-6,c(V_(2)O_(3))=0.5 mol/L,p(H;)=4 MPa,m(PdCl;)=10 mg,T=250℃,and t=2.5 h.展开更多
As part of efforts to reduce anthropogenic CO_(2) emissions by the steelmaking industry,this study investigated the direct reduction of industrially produced hematite pellets with H_(2) using the Doehlert experimental...As part of efforts to reduce anthropogenic CO_(2) emissions by the steelmaking industry,this study investigated the direct reduction of industrially produced hematite pellets with H_(2) using the Doehlert experimental design to evaluate the effect of pellet diameter(10.5-16.5 mm),porosity(0.36-0.44),and temperature(600-1200℃).A strong interactive effect between temperature and pellet size was observed,indicating that these variables cannot be considered independently.The increase in temperature and decrease in pellet size considerably favor the reduction rate,while porosity did not show a relevant effect.The change in pellet size during the reduction was negligible,except at elevated temperatures due to crack formation.A considerable decrease in mechanical strength at high temperatures suggests a maximum process operating temperature of 900℃.Good predictive capacity was achieved using the modified grain model to simulate the three consecutive non-catalytic gas-solid reactions,considering different pellet sizes and porosities,changes during the reaction from 800 to 900℃.However,for other temperatures,different mechanisms of structural modifications must be considered in the modeling.These results represent significant contributions to the development of ore pellets for CO_(2)-free steelmaking technology.展开更多
Hydrogen evolution reaction(HER)is the major cathodic reaction which competes CO2 reduction reaction(CO2 RR)on Pt electrode.Molecular level understanding on how these two reactions interact with each other and what th...Hydrogen evolution reaction(HER)is the major cathodic reaction which competes CO2 reduction reaction(CO2 RR)on Pt electrode.Molecular level understanding on how these two reactions interact with each other and what the key factors are of CO2 RR kinetics and selectivity will be of great help in optimizing electrolysers for CO2 reduction.In this work,we report our results of hydrogen evolution and CO2 reduction on Pt(111)and Pt film electrodes in CO2 saturated acid solution by cyclic voltammetry and infrared spectroscopy.In solution with pH>2,the major process is HER and the interfacial pH increases abruptly during HER;COad is the only adsorbed intermediate detected in CO2 reduction by infrared spectroscopy;the rate for COad formation increases with the coverage of UPD-H and reaches maximum at the onset potential for HER;the decrease of COad formation under HER is attributed to the available limited sites and the limited residence time for the reduction intermediate(Had),which is necessary for CO2 adsorption and reduction.展开更多
The purpose of this study was to investigate the effect of preadsorbed CO at different temperatures, calcination temperatures, the combined influence of reduction temperature and time, and pretreatment using hydrogen ...The purpose of this study was to investigate the effect of preadsorbed CO at different temperatures, calcination temperatures, the combined influence of reduction temperature and time, and pretreatment using hydrogen or syngas as reduction agents on the F-T synthesis (FTS) activity and selectivity of Co/Al2O3 catalyst. The reactivity of the carbon species at higher preadsorption temperature with H2 in TPSR decreased, whereas the carbon-containing species showed higher reactivity over Co/Al2O3 catalyst with low calcination temperature. This agreed well with the order of catalytic activity for F-T synthesis on this catalyst. The catalytic activity of the catalyst varied with reduction temperature and time remarkably. CODEX optimization gave an optimum reduction temperature of 756 K and reduction time of 6.2 h and estimated C5+ yield perfectly. The pretreatment of Co/Al2O3 catalyst with different reduction agents (hydrogen or syngas) showed important influences on the catalytic performance. A high CO conversion and C5+ yield were obtained on the catalyst reduced by hydrogen, whereas methane selectivity on the catalyst reduced by syngas was much higher than that on the catalyst reduced by hydrogen.展开更多
Photocatalytic CO_(2)reduction to produce high value-added carbon-based fuel has been proposed as a promising approach to mitigate global warming issues.However,the conversion efficiency and product selectivity are st...Photocatalytic CO_(2)reduction to produce high value-added carbon-based fuel has been proposed as a promising approach to mitigate global warming issues.However,the conversion efficiency and product selectivity are still low due to the sluggish dynamics of transfer processes involved in proton-assisted multi-electron reactions.Lowering the formation energy barriers of intermediate products is an effective method to enhance the selectivity and productivity of final products.In this study,we aim to regulate the surface electronic structure of Bi_(2)WO_(6)by doping surface chlorine atoms to achieve effective photocatalytic CO_(2)reduction.Surface Cl atoms can enhance the absorption ability of light,affect its energy band structure and promote charge separation.Combined with DFT calculations,it is revealed that surface Cl atoms can not only change the surface charge distribution which affects the competitive adsorption of H_(2)O and CO_(2),but also lower the formation energy barrier of intermediate products to generate more intermediate*COOH,thus facilitating CO production.Overall,this study demonstrates a promising surface halogenation strategy to enhance the photocatalytic CO_(2)reduction activity of a layered structure Bi-based catalyst.展开更多
Tungstated zirconia(WO_(3)/ZrO_(2))solid acid catalysts with different WO_(3) contents were prepared by a hydrothermal method and then used in the catalytic aquathermolysis of heavy oil from Xinjiang.The WO_(3)/ZrO_(2...Tungstated zirconia(WO_(3)/ZrO_(2))solid acid catalysts with different WO_(3) contents were prepared by a hydrothermal method and then used in the catalytic aquathermolysis of heavy oil from Xinjiang.The WO_(3)/ZrO_(2) solid acid catalyst was characterized by a range of characterization methods,including X-ray diffraction,NH3-temperature programmed desorption,and pyridine infrared spectroscopy.The WO_(3) content of the WO_(3)/ZrO_(2) catalysts had an important impact on the structure and property of the catalysts.When the WO_(3) mass fraction was 20%,it facilitated the formation of tetragonal zirconia,thereby enhancing the creation of robust acidic sites.Acidity is considered to have a strong impact on the catalytic performance of the aquathermolysis of heavy oil.When the catalyst containing 20%WO_(3) was used to catalyze the aquathermolysis of heavy oil under conditions of 14.5 MPa,340℃,and 24 h,the viscosity of heavy oil decreased from 47266 to 5398 mPa·s and the viscosity reduction rate reached 88.6%.The physicochemical properties of heavy oil before and after the aquathermolysis were analyzed using a saturates,aromatics,resins,and asphaltenes analysis,gas chromatography,elemental analysis,densimeter etc.After the aquathermolysis,the saturate and aromatic contents significantly increased from 43.3%to 48.35%and 19.47%to 21.88%,respectively,with large reductions in the content of resin and asphaltene from 28.22%to 25.06%and 5.36%to 2.03%,respectively.The sulfur and nitrogen contents,and the density of the oil were significantly decreased.These factors were likely the main reasons for promoting the viscosity reduction of heavy oil during the aquathermolysis over the WO_(3)/ZrO_(2) solid acid catalysts.展开更多
K2Ti6O13 whiskers were synthesized by conventional sol-gel method, sono-chemical assisted and microwave assisted sol-gel method in order to obtain catalysts with different particle sizes and to modify their optical, t...K2Ti6O13 whiskers were synthesized by conventional sol-gel method, sono-chemical assisted and microwave assisted sol-gel method in order to obtain catalysts with different particle sizes and to modify their optical, textural and electrochemical properties. These modifications improved their photocatalytic activity for H2 evolution and CO2 photo-reduction. Long K2Ti6O13 whiskers prepared by ultrasound assisted sol-gel method are the most active photocatalysts for the hydrogen evolution reaction using pure water as reactant (U-SG, 10,065 μmol g^-1). In contrast, an opposite behavior was observed using a mixture of ethanol-water, where the highest activity was achieved by the shortest and less crystalline K2Ti6O13 whiskers (C-SG, 3,2871 μmol g^-1). In case of CO2 photo-reduction, long whiskers that were also prepared by the sono-chemical assisted sol-gel method were the most active to transform CO2 to formaldehyde, methane, methanol and hydrogen. The EFB value of this catalyst is located very close to the potential for formaldehyde production and favors the selectivity to this organic product.展开更多
In-plane epitaxial growth of ZnIn_(2)S_(4) nanosheets on the surface of hexagonal phase WO_(3) nanorods was achieved by a facile solvothermal method.The unique 3D heterostructure not only enlarged the specific surface...In-plane epitaxial growth of ZnIn_(2)S_(4) nanosheets on the surface of hexagonal phase WO_(3) nanorods was achieved by a facile solvothermal method.The unique 3D heterostructure not only enlarged the specific surface area,but also red-shifted the absorption edge from 381 to 476 nm to improve the light harvesting ability,which largely enhanced the photocatalytic hydrogen evolution.The H_(2) production rate of the best performing ZnIn_(2)S_(4)/WO_(3) photocatalyst(ZIS-2.5/W,the material with a molar rate of ZnIn_(2)S_(4)(ZIS)to WO_(3)(W)of 2.5)was 300μmol·g^(–1)·h^(–1),around 417 times and 2 times higher than the rates of pristine WO_(3) and ZnIn_(2)S_(4),respectively.The apparent quantum efficiency for ZIS-2.5/W composite was up to 2.81%at 400 nm.Based on the difference in Fermi levels between WO_(3) and ZnIn_(2)S_(4),and the distribution of the redox active sites on WO_(3)/ZnIn_(2)S_(4) heterostructure,a S-scheme electron transfer mechanism was proposed to illustrate the improved photocatalytic activity of WO_(3)/ZnIn_(2)S_(4) heterojunction,which not only stimulated the spatial separation of the photogenerated charge carriers,but also maintained the strong reduction/oxidation ability of the photocatalyst.展开更多
Solar‐energy‐driven catalytic CO_(2) reduction for the production of value‐added carbon‐based materials and chemical raw materials has attracted great interest to alleviate the global climate change and energy cri...Solar‐energy‐driven catalytic CO_(2) reduction for the production of value‐added carbon‐based materials and chemical raw materials has attracted great interest to alleviate the global climate change and energy crisis.The production of multicarbon(C2)products through CO_(2) reduction is extremely attractive,however,the yield and selectivity of C2 products remain low because of the low reaction temperature required and the low photoelectron density of the substrate.Here,we introduce WO3–x,which contains oxygen vacancies and exhibits an excellent photothermal conversion efficiency,to improve the generation of C2 products(C2H4 and C2H6)under simulated sunlight(UV‐Vis‐IR)irradiation.WO3–x produced 5.30 and 0.93μmol·g^(–1)C2H4 and C2H6,respectively,after 4 h,with a selectivity exceeding 34%.In situ Fourier transform infrared spectra and theoretical calculations showed that the oxygen vacancies enhanced the water activation and hydrogenation of adsorbed CO for the formation of C2 products via C–C coupling from CH2/CH3 intermediates.The findings of this study could assist in the design of highly active solar‐energy‐driven catalysts to produce C–C coupling products through CO2 reduction.展开更多
In this manuscript,Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6) nanocomposites was fabricated via an ultrasonic-assisted process.The activity of the as-obtained Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6) nanocomposites for photocatalytic CO_(2) ...In this manuscript,Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6) nanocomposites was fabricated via an ultrasonic-assisted process.The activity of the as-obtained Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6) nanocomposites for photocatalytic CO_(2) reduction was studied under visible light.The as-obtained Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6) nanocomposites show a superior activity for photocatalytic CO_(2) reduction to produce CH4 and CO,with an optimum activity achieved over 0.5 Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6).The obvious superior activity observed over Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6) nanocomposites as compared with bare Cs_(2)AgBiBr_(6) and bare Bi_(2)WO_(6) as well as a mechanical mixture of Cs_(2)AgBiBr_(6) and Bi_(2)WO_(6) can be owe to the fabrication of an efficient S-scheme heterojunction,which accelerates the separation of the photogenerated charge carriers in Cs_(2)AgBiBr_(6) and Bi_(2)WO_(6) without sacrificing the high redox capability of Cs_(2)AgBiBr_(6) and Bi_(2)WO_(6).This work demonstrates that the coupling of two photocatalytic materials with staggered band alignment to form an S-scheme heterojunction is an effective strategy to develop efficient photocatalytic systems and also highlights the promising role of using lead free perovskites in photocatalysis.展开更多
Two-electron(2 e^(-))oxygen reduction reaction(ORR)shows great promise for on-site electrochemical synthesis of hydrogen peroxide(H_(2)O_(2)).However,it is still a great challenge to design efficient electrocatalysts ...Two-electron(2 e^(-))oxygen reduction reaction(ORR)shows great promise for on-site electrochemical synthesis of hydrogen peroxide(H_(2)O_(2)).However,it is still a great challenge to design efficient electrocatalysts for H_(2)O_(2)synthesis.To address this issue,the logical design of the active site by controlling the geometric and electronic structures is urgently desired.Therefore,using density functional theory(DFT)computations,two kinds of hybrid double-atom supported on C_(2)N nanosheet(RuCu@C_(2)N and PdCu@C_(2)N)are screened out and their H_(2)O_(2)performances are predicted.PdCu@C_(2)N exhibits higher activity for H_(2)O_(2)synthesis with a lower overpotential of 0.12 V than RuCu@C_(2)N(0.59 V),Ru_(3)Cu(110)facet(0.60 V),and PdCu(110)facet(0.54 V).In aqueous phase,the adsorbed O_(2)is further stabilized with bulk H_(2)0 and the thermodynamic rate-determining step of 2 e^(-) ORR change.The activation barrier on PdCu@C_(2)N is 0.43 eV lower than the one on RuCu@C_(2)N with 0.68 eV.PdCu@C_(2)N is near the top of 2 e^(-) ORR volcano plot,and exhibits high selectivity of H_(2)O_(2.)This work provides guidelines for designing highly effective hybrid double-atom electrocatalysts(HDACs)for H_(2)O_(2)synthesis.展开更多
The development of distinguished photocatalysts with high photo-carrier disassociation and photo-redox power for efficient elimination of pollutants in water is of great significance but still a grand challenge.Herein...The development of distinguished photocatalysts with high photo-carrier disassociation and photo-redox power for efficient elimination of pollutants in water is of great significance but still a grand challenge.Herein,a novel Cd_(0.5)Zn_(0.5)S/Bi_(2)WO_(6) S-scheme heterojunction was built up by integrating Cd0.5Zn0.5S nanoparticles on Bi2WO6 microspheres via a simple route.The S-scheme charge transfer mode substantially boosts the high-energetic electrons/holes spatial detachment and conservation on the Cd_(0.5)Zn_(0.5)S(reduction)and Bi_(2)WO_(6)(oxidation),respectively,as well as effectively suppresses the photo-corrosion of Cd_(0.5)Zn_(0.5)S,rendering Cd_(0.5)Zn_(0.5)S/Bi_(2)WO_(6) photocatalysts with superior redox ability.The optimal Cd_(0.5)Zn_(0.5)S/Bi_(2)WO_(6) heterojunction achieves exceptional visible-light-driven photocatalytic tetracycline degradation and Cr(VI)reduction efficiency,3.2(1.9)-time and 33.6(1.6)-time stronger than that of neat Bi_(2)WO_(6)(Cd_(0.5)Zn_(0.5)S),while retaining the superior stability and reusability.Quenching test,mass spectrometry analysis,and toxicity assessment based on Quantitative Structure Activity Relationships.calculation unravel the prime active substances,intermediates,photo-degradation pathway,and intermediate eco-toxicity in photocatalytic process.This research not only offers a potential photocatalyst for aquatic environment protection but also promotes the exploration of novel and powerful chalcogenides-based S-scheme photocatalysts for environment protection.展开更多
The efficient utilization of photocatalytic technology is essential for clean energy.Bismuth-based multimetal oxides(Bi_(2)WO_(6),Bi_(2)MoO_(6),BiVO_(4)and Bi_(4)Ti_(3)O_(12))have aroused widespread attention as a vis...The efficient utilization of photocatalytic technology is essential for clean energy.Bismuth-based multimetal oxides(Bi_(2)WO_(6),Bi_(2)MoO_(6),BiVO_(4)and Bi_(4)Ti_(3)O_(12))have aroused widespread attention as a visible light responsive photocatalyst for hydrogen evolution due to their low cost,nontoxicity,modifiable morphology,and outstanding optical and chemical properties.Nevertheless,the photocatalytic activities of pure materials are unsatisfactory because of their relative small specific surface area,poor quantum yield,and the rapid recombination of photogenerated carriers.Therefore,some modification strategies,including morphological control,semiconductor combination,doping,and defect engineering,have been systematically studied to enhance photocatalytic H_(2)evolution activity in the past few years.Herein,we summarize the recent research progress on bismuth-based photocatalysts,pointing out the prospects,opportunities and challenges of bismuth-based photocatalysts.Eventually,we aims to put forward valuable suggestions for designing of bismuth-based photocatalysts applied in hydrogen production on the premise of consolidating the existing theoretical basis of photocatalysis.展开更多
Converting CO2 to carbon-containing fuels is an effective approach to relieving energy shortages.Carbon quantum dots(CQDs) have shown distinct properties and attracted tremendous interest in CO2 reduction.Herein,we re...Converting CO2 to carbon-containing fuels is an effective approach to relieving energy shortages.Carbon quantum dots(CQDs) have shown distinct properties and attracted tremendous interest in CO2 reduction.Herein,we report a joint experimental-computational mechanistic study of photoreduction CO2 to CO on the model catalyst 9-hydroxyphenal-1-one(HPHN) CQDs with known structure.Our theoretical calculations reveal that the rate-determining step is COOH·formation,which is closely related to the proton and electron transfer induced by hydrogen bonding in the excited state.According to the calculated volcano plot,the solution we proposed is addition Zn^(2+) ions.The active center changed from the hydroxyl oxygen atom to the Zn atom and the barrier of the COOH·formation step is noticeably decreased when Zn^(2+) ions are added.It is further confirmed by the experimental data that the activity of CO2 reduction increases 2.9 times when Zn^(2+) ions are added.展开更多
The exploration of sustainable energy utilization requires the imple-mentation of advanced electrochemical devices for efficient energy conversion and storage,which are enabled by the usage of cost-effective,high-perf...The exploration of sustainable energy utilization requires the imple-mentation of advanced electrochemical devices for efficient energy conversion and storage,which are enabled by the usage of cost-effective,high-performance electro-catalysts.Currently,heterogeneous atomically dispersed catalysts are considered as potential candidates for a wide range of applications.Compared to conventional cata-lysts,atomically dispersed metal atoms in carbon-based catalysts have more unsatu-rated coordination sites,quantum size effect,and strong metal-support interactions,resulting in exceptional catalytic activity.Of these,dual-atomic catalysts(DACs)have attracted extensive attention due to the additional synergistic effect between two adja-cent metal atoms.DACs have the advantages of full active site exposure,high selectiv-ity,theoretical 100%atom utilization,and the ability to break the scaling relationship of adsorption free energy on active sites.In this review,we summarize recent research advancement of DACs,which includes(1)the comprehensive understanding of the synergy between atomic pairs;(2)the synthesis of DACs;(3)characterization meth-ods,especially aberration-corrected scanning transmission electron microscopy and synchrotron spectroscopy;and(4)electrochemical energy-related applications.The last part focuses on great potential for the electrochemical catalysis of energy-related small molecules,such as oxygen reduction reaction,CO_(2) reduction reaction,hydrogen evolution reaction,and N_(2) reduction reaction.The future research challenges and opportunities are also raised in prospective section.展开更多
文摘The hydrogen reduction of tungsten oxides WO_(272)and WO_2 were studied directly using high-temperature X-ray diffraction analysis,The pure β-W was obtained from the reduction of WO_(272)The transformation of β-W to x-W was also studied in both hydrogen and nitrogen.The forming condition of β-W from WO_2 was discussed.Finally.a complete schematic diagram of reduction of tungsten oxides was given in this paper.
基金funding support from the National Natural Science Foundation of China(2200206852272222,and 52072197)+12 种基金the Taishan Scholar Young Talent Program(tsqn201909114)the Youth Innovation and Technology Foundation of Shandong Higher Education Institutions,China(2019KJC004)the Outstanding Youth Foundation of Shandong Province,China(ZR2019JQ14)the Major Basic Research Program of Natural Science Foundation of Shandong Province under Grant No.ZR2020ZD09Youth Innovation Team Development Program of Shandong Higher Education Institutions(2022KJ155)the Major Scientific and Technological Innovation Project(2019JZZY020405)the Shandong Province“Double-Hundred Talent Plan”(WST2020003)Project funded by the China Postdoctoral Science Foundation(2021M691700)the Natural Science Foundation of Shandong Province of China(ZR2019BB002ZR2018BB031)the Postdoctoral Innovation Project of Shandong Province(SDCXZG-202203021)the Scientific and Technological Innovation Promotion Project for Small-medium Enterprises of Shandong Province(2022TSGC1257)the Major Research Program of Jining City(2020ZDZP024)。
文摘Constructing highly-efficient electrocatalysts toward hydrogen evolution reaction(HER)/oxygen evolution reaction(OER)/oxygen reduction reaction(ORR)with excellent stability is quite important for the development of renewable energy-related applications.Herein,Co-Ru based compounds supported on nitrogen doped two-dimensional(2D)carbon nanosheets(NCN)are developed via one step pyrolysis procedure(Co-Ru/NCN)for HER/ORR and following low-temperature oxidation process(Co-Ru@RuO_(x)/NCN)for OER.The specific 2D morphology guarantees abundant active sites exposure.Furthermore,the synergistic effects arising from the interaction between Co and Ru are crucial in enhancing the catalytic performance.Thus,the resulting Co-Ru/NCN shows remarkable electrocatalytic performance for HER(70 mV at 10 mA cm^(-2))in 1 M KOH and ORR(half-wave potential E_(1/2)=0.81 V)in 0.1 M KOH.Especially,the Co-Ru@RuO_(x)/NCN obtained by oxidation exhibits splendid OER performance in both acid(230 mV at 10 mA cm^(-2))and alkaline media(270 mV at 10 mA cm^(-2))coupled with excellent stability.Consequently,the fabricated two-electrode water-splitting device exhibits excellent performance in both acidic and alkaline environments.This research provides a promising avenue for the advancement of multifunctional nanomaterials.
基金financially supported by the National Key R&D Program of China(No.2020YFC1909700)Outstanding Young and Middle-aged Science and Technology Innovation Team Project of Hubei Province,China(No.T201802)the National Natural Science Foundation of China(No.52004187)。
文摘Solution-phase hydrogen reduction(Sp HR)was introduced into V_(2)O_(3)preparation to overcome disadvantages of traditional reduction roasting,which include a long process,high energy consumption,and generation of pollution.The research mainly focuses onφ-pH diagrams and kinetics of SpHR.Thermodynamic analysis ofφ-pH diagrams for the V-H_(2)O system demonstrates that V_(2)O_(3)preparation via Sp HR requires a high temperature,a high vanadium concentration,and sufficient hydrogen in acidic solution.Kinetic analyses show that the activation energy of V_(2)O_(3)preparation via SpHR is 38.0679 k J/mol,indicating that the reduction is controlled by a combination of interfacial chemical reaction and internal diffusion.Effects of H;partial pressure(slope K=0.05246)on the reaction rate is not as significant as the vanadium concentration(K=1.58872).V_(2)O_(3)crystals with a purity of 99.59%and a vanadium precipitation rate of 99.83%were obtained under the following conditions:pH=5-6,c(V_(2)O_(3))=0.5 mol/L,p(H;)=4 MPa,m(PdCl;)=10 mg,T=250℃,and t=2.5 h.
基金Institute of Technological Research–IPT,Fundcao de AmparoàPesquisa do Estado de Sao PauloBrazil[Process 2019/05840-3]+1 种基金Conselho Nacional de Desenvolvimento Científico e TecnológicoBrazil[Process 167470/2018-3]。
文摘As part of efforts to reduce anthropogenic CO_(2) emissions by the steelmaking industry,this study investigated the direct reduction of industrially produced hematite pellets with H_(2) using the Doehlert experimental design to evaluate the effect of pellet diameter(10.5-16.5 mm),porosity(0.36-0.44),and temperature(600-1200℃).A strong interactive effect between temperature and pellet size was observed,indicating that these variables cannot be considered independently.The increase in temperature and decrease in pellet size considerably favor the reduction rate,while porosity did not show a relevant effect.The change in pellet size during the reduction was negligible,except at elevated temperatures due to crack formation.A considerable decrease in mechanical strength at high temperatures suggests a maximum process operating temperature of 900℃.Good predictive capacity was achieved using the modified grain model to simulate the three consecutive non-catalytic gas-solid reactions,considering different pellet sizes and porosities,changes during the reaction from 800 to 900℃.However,for other temperatures,different mechanisms of structural modifications must be considered in the modeling.These results represent significant contributions to the development of ore pellets for CO_(2)-free steelmaking technology.
基金supported by the National Natural Science Foundation of China (No.21473175 and No.21273215)the Ministry of Science and Technology of China (No.2015CB932301)
文摘Hydrogen evolution reaction(HER)is the major cathodic reaction which competes CO2 reduction reaction(CO2 RR)on Pt electrode.Molecular level understanding on how these two reactions interact with each other and what the key factors are of CO2 RR kinetics and selectivity will be of great help in optimizing electrolysers for CO2 reduction.In this work,we report our results of hydrogen evolution and CO2 reduction on Pt(111)and Pt film electrodes in CO2 saturated acid solution by cyclic voltammetry and infrared spectroscopy.In solution with pH>2,the major process is HER and the interfacial pH increases abruptly during HER;COad is the only adsorbed intermediate detected in CO2 reduction by infrared spectroscopy;the rate for COad formation increases with the coverage of UPD-H and reaches maximum at the onset potential for HER;the decrease of COad formation under HER is attributed to the available limited sites and the limited residence time for the reduction intermediate(Had),which is necessary for CO2 adsorption and reduction.
基金The National Basic Research Program of China (973 Program) (No. 2005CB221402)China National Petroleum Corporation
文摘The purpose of this study was to investigate the effect of preadsorbed CO at different temperatures, calcination temperatures, the combined influence of reduction temperature and time, and pretreatment using hydrogen or syngas as reduction agents on the F-T synthesis (FTS) activity and selectivity of Co/Al2O3 catalyst. The reactivity of the carbon species at higher preadsorption temperature with H2 in TPSR decreased, whereas the carbon-containing species showed higher reactivity over Co/Al2O3 catalyst with low calcination temperature. This agreed well with the order of catalytic activity for F-T synthesis on this catalyst. The catalytic activity of the catalyst varied with reduction temperature and time remarkably. CODEX optimization gave an optimum reduction temperature of 756 K and reduction time of 6.2 h and estimated C5+ yield perfectly. The pretreatment of Co/Al2O3 catalyst with different reduction agents (hydrogen or syngas) showed important influences on the catalytic performance. A high CO conversion and C5+ yield were obtained on the catalyst reduced by hydrogen, whereas methane selectivity on the catalyst reduced by syngas was much higher than that on the catalyst reduced by hydrogen.
基金supported by the National Natural Science Foundation of China(Grant No.51708078)Natural Science Foundation of Chongqing(Grant No.CSTB2022NSCQ-MSX0815)+2 种基金Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJQN202200542)the Chongqing Innovative Research Group Project(Grant No.CXQT21015)Foundation of Chongqing Normal University(22XLB022).
文摘Photocatalytic CO_(2)reduction to produce high value-added carbon-based fuel has been proposed as a promising approach to mitigate global warming issues.However,the conversion efficiency and product selectivity are still low due to the sluggish dynamics of transfer processes involved in proton-assisted multi-electron reactions.Lowering the formation energy barriers of intermediate products is an effective method to enhance the selectivity and productivity of final products.In this study,we aim to regulate the surface electronic structure of Bi_(2)WO_(6)by doping surface chlorine atoms to achieve effective photocatalytic CO_(2)reduction.Surface Cl atoms can enhance the absorption ability of light,affect its energy band structure and promote charge separation.Combined with DFT calculations,it is revealed that surface Cl atoms can not only change the surface charge distribution which affects the competitive adsorption of H_(2)O and CO_(2),but also lower the formation energy barrier of intermediate products to generate more intermediate*COOH,thus facilitating CO production.Overall,this study demonstrates a promising surface halogenation strategy to enhance the photocatalytic CO_(2)reduction activity of a layered structure Bi-based catalyst.
基金the financial support from the Open Fund Project of the National Oil Shale Exploitation Research and Development Center,China(No.33550000-22-ZC0613-0255)the Graduate Student Innovation and Practical Ability Training Program of Xi’an Shiyou University(No.YCS23213098)+3 种基金the National Natural Science Foundation of China(No.52274039)the Natural Science Basic Research Plan in Shaanxi Province of China(Program No.2024JC-YBMS-085)the CNPC Innovation Found(No.2022DQ02-0402)The authors also thank the Modern Analysis and Test Center of Xi’an Shiyou University for their help with the characterization of catalysts and analysis of products.
文摘Tungstated zirconia(WO_(3)/ZrO_(2))solid acid catalysts with different WO_(3) contents were prepared by a hydrothermal method and then used in the catalytic aquathermolysis of heavy oil from Xinjiang.The WO_(3)/ZrO_(2) solid acid catalyst was characterized by a range of characterization methods,including X-ray diffraction,NH3-temperature programmed desorption,and pyridine infrared spectroscopy.The WO_(3) content of the WO_(3)/ZrO_(2) catalysts had an important impact on the structure and property of the catalysts.When the WO_(3) mass fraction was 20%,it facilitated the formation of tetragonal zirconia,thereby enhancing the creation of robust acidic sites.Acidity is considered to have a strong impact on the catalytic performance of the aquathermolysis of heavy oil.When the catalyst containing 20%WO_(3) was used to catalyze the aquathermolysis of heavy oil under conditions of 14.5 MPa,340℃,and 24 h,the viscosity of heavy oil decreased from 47266 to 5398 mPa·s and the viscosity reduction rate reached 88.6%.The physicochemical properties of heavy oil before and after the aquathermolysis were analyzed using a saturates,aromatics,resins,and asphaltenes analysis,gas chromatography,elemental analysis,densimeter etc.After the aquathermolysis,the saturate and aromatic contents significantly increased from 43.3%to 48.35%and 19.47%to 21.88%,respectively,with large reductions in the content of resin and asphaltene from 28.22%to 25.06%and 5.36%to 2.03%,respectively.The sulfur and nitrogen contents,and the density of the oil were significantly decreased.These factors were likely the main reasons for promoting the viscosity reduction of heavy oil during the aquathermolysis over the WO_(3)/ZrO_(2) solid acid catalysts.
基金CONACYT (CB-2014-237049, PDCPN-2015-487 and Ph. D. scholarship 635249) for the financial support
文摘K2Ti6O13 whiskers were synthesized by conventional sol-gel method, sono-chemical assisted and microwave assisted sol-gel method in order to obtain catalysts with different particle sizes and to modify their optical, textural and electrochemical properties. These modifications improved their photocatalytic activity for H2 evolution and CO2 photo-reduction. Long K2Ti6O13 whiskers prepared by ultrasound assisted sol-gel method are the most active photocatalysts for the hydrogen evolution reaction using pure water as reactant (U-SG, 10,065 μmol g^-1). In contrast, an opposite behavior was observed using a mixture of ethanol-water, where the highest activity was achieved by the shortest and less crystalline K2Ti6O13 whiskers (C-SG, 3,2871 μmol g^-1). In case of CO2 photo-reduction, long whiskers that were also prepared by the sono-chemical assisted sol-gel method were the most active to transform CO2 to formaldehyde, methane, methanol and hydrogen. The EFB value of this catalyst is located very close to the potential for formaldehyde production and favors the selectivity to this organic product.
文摘In-plane epitaxial growth of ZnIn_(2)S_(4) nanosheets on the surface of hexagonal phase WO_(3) nanorods was achieved by a facile solvothermal method.The unique 3D heterostructure not only enlarged the specific surface area,but also red-shifted the absorption edge from 381 to 476 nm to improve the light harvesting ability,which largely enhanced the photocatalytic hydrogen evolution.The H_(2) production rate of the best performing ZnIn_(2)S_(4)/WO_(3) photocatalyst(ZIS-2.5/W,the material with a molar rate of ZnIn_(2)S_(4)(ZIS)to WO_(3)(W)of 2.5)was 300μmol·g^(–1)·h^(–1),around 417 times and 2 times higher than the rates of pristine WO_(3) and ZnIn_(2)S_(4),respectively.The apparent quantum efficiency for ZIS-2.5/W composite was up to 2.81%at 400 nm.Based on the difference in Fermi levels between WO_(3) and ZnIn_(2)S_(4),and the distribution of the redox active sites on WO_(3)/ZnIn_(2)S_(4) heterostructure,a S-scheme electron transfer mechanism was proposed to illustrate the improved photocatalytic activity of WO_(3)/ZnIn_(2)S_(4) heterojunction,which not only stimulated the spatial separation of the photogenerated charge carriers,but also maintained the strong reduction/oxidation ability of the photocatalyst.
文摘Solar‐energy‐driven catalytic CO_(2) reduction for the production of value‐added carbon‐based materials and chemical raw materials has attracted great interest to alleviate the global climate change and energy crisis.The production of multicarbon(C2)products through CO_(2) reduction is extremely attractive,however,the yield and selectivity of C2 products remain low because of the low reaction temperature required and the low photoelectron density of the substrate.Here,we introduce WO3–x,which contains oxygen vacancies and exhibits an excellent photothermal conversion efficiency,to improve the generation of C2 products(C2H4 and C2H6)under simulated sunlight(UV‐Vis‐IR)irradiation.WO3–x produced 5.30 and 0.93μmol·g^(–1)C2H4 and C2H6,respectively,after 4 h,with a selectivity exceeding 34%.In situ Fourier transform infrared spectra and theoretical calculations showed that the oxygen vacancies enhanced the water activation and hydrogenation of adsorbed CO for the formation of C2 products via C–C coupling from CH2/CH3 intermediates.The findings of this study could assist in the design of highly active solar‐energy‐driven catalysts to produce C–C coupling products through CO2 reduction.
文摘In this manuscript,Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6) nanocomposites was fabricated via an ultrasonic-assisted process.The activity of the as-obtained Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6) nanocomposites for photocatalytic CO_(2) reduction was studied under visible light.The as-obtained Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6) nanocomposites show a superior activity for photocatalytic CO_(2) reduction to produce CH4 and CO,with an optimum activity achieved over 0.5 Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6).The obvious superior activity observed over Cs_(2)AgBiBr_(6)/Bi_(2)WO_(6) nanocomposites as compared with bare Cs_(2)AgBiBr_(6) and bare Bi_(2)WO_(6) as well as a mechanical mixture of Cs_(2)AgBiBr_(6) and Bi_(2)WO_(6) can be owe to the fabrication of an efficient S-scheme heterojunction,which accelerates the separation of the photogenerated charge carriers in Cs_(2)AgBiBr_(6) and Bi_(2)WO_(6) without sacrificing the high redox capability of Cs_(2)AgBiBr_(6) and Bi_(2)WO_(6).This work demonstrates that the coupling of two photocatalytic materials with staggered band alignment to form an S-scheme heterojunction is an effective strategy to develop efficient photocatalytic systems and also highlights the promising role of using lead free perovskites in photocatalysis.
基金supported by the National Natural Science Foundation of China(Grant No 21625604,21671172,21776251,21706229 and 91934302)。
文摘Two-electron(2 e^(-))oxygen reduction reaction(ORR)shows great promise for on-site electrochemical synthesis of hydrogen peroxide(H_(2)O_(2)).However,it is still a great challenge to design efficient electrocatalysts for H_(2)O_(2)synthesis.To address this issue,the logical design of the active site by controlling the geometric and electronic structures is urgently desired.Therefore,using density functional theory(DFT)computations,two kinds of hybrid double-atom supported on C_(2)N nanosheet(RuCu@C_(2)N and PdCu@C_(2)N)are screened out and their H_(2)O_(2)performances are predicted.PdCu@C_(2)N exhibits higher activity for H_(2)O_(2)synthesis with a lower overpotential of 0.12 V than RuCu@C_(2)N(0.59 V),Ru_(3)Cu(110)facet(0.60 V),and PdCu(110)facet(0.54 V).In aqueous phase,the adsorbed O_(2)is further stabilized with bulk H_(2)0 and the thermodynamic rate-determining step of 2 e^(-) ORR change.The activation barrier on PdCu@C_(2)N is 0.43 eV lower than the one on RuCu@C_(2)N with 0.68 eV.PdCu@C_(2)N is near the top of 2 e^(-) ORR volcano plot,and exhibits high selectivity of H_(2)O_(2.)This work provides guidelines for designing highly effective hybrid double-atom electrocatalysts(HDACs)for H_(2)O_(2)synthesis.
文摘The development of distinguished photocatalysts with high photo-carrier disassociation and photo-redox power for efficient elimination of pollutants in water is of great significance but still a grand challenge.Herein,a novel Cd_(0.5)Zn_(0.5)S/Bi_(2)WO_(6) S-scheme heterojunction was built up by integrating Cd0.5Zn0.5S nanoparticles on Bi2WO6 microspheres via a simple route.The S-scheme charge transfer mode substantially boosts the high-energetic electrons/holes spatial detachment and conservation on the Cd_(0.5)Zn_(0.5)S(reduction)and Bi_(2)WO_(6)(oxidation),respectively,as well as effectively suppresses the photo-corrosion of Cd_(0.5)Zn_(0.5)S,rendering Cd_(0.5)Zn_(0.5)S/Bi_(2)WO_(6) photocatalysts with superior redox ability.The optimal Cd_(0.5)Zn_(0.5)S/Bi_(2)WO_(6) heterojunction achieves exceptional visible-light-driven photocatalytic tetracycline degradation and Cr(VI)reduction efficiency,3.2(1.9)-time and 33.6(1.6)-time stronger than that of neat Bi_(2)WO_(6)(Cd_(0.5)Zn_(0.5)S),while retaining the superior stability and reusability.Quenching test,mass spectrometry analysis,and toxicity assessment based on Quantitative Structure Activity Relationships.calculation unravel the prime active substances,intermediates,photo-degradation pathway,and intermediate eco-toxicity in photocatalytic process.This research not only offers a potential photocatalyst for aquatic environment protection but also promotes the exploration of novel and powerful chalcogenides-based S-scheme photocatalysts for environment protection.
基金This research was supported by National Natural Science Foundation of China(21706132 and 21976093)Jiangsu Provincial Specially Appointed Professors Foundation,The Startup Foundation for Introducing Talent of NUIST.
文摘The efficient utilization of photocatalytic technology is essential for clean energy.Bismuth-based multimetal oxides(Bi_(2)WO_(6),Bi_(2)MoO_(6),BiVO_(4)and Bi_(4)Ti_(3)O_(12))have aroused widespread attention as a visible light responsive photocatalyst for hydrogen evolution due to their low cost,nontoxicity,modifiable morphology,and outstanding optical and chemical properties.Nevertheless,the photocatalytic activities of pure materials are unsatisfactory because of their relative small specific surface area,poor quantum yield,and the rapid recombination of photogenerated carriers.Therefore,some modification strategies,including morphological control,semiconductor combination,doping,and defect engineering,have been systematically studied to enhance photocatalytic H_(2)evolution activity in the past few years.Herein,we summarize the recent research progress on bismuth-based photocatalysts,pointing out the prospects,opportunities and challenges of bismuth-based photocatalysts.Eventually,we aims to put forward valuable suggestions for designing of bismuth-based photocatalysts applied in hydrogen production on the premise of consolidating the existing theoretical basis of photocatalysis.
基金supported by the National Natural Science Foundation of China (Grant Nos. 21677029, 21606040)the Fundamental Research Funds for the Central Universities (DUT18LK26)。
文摘Converting CO2 to carbon-containing fuels is an effective approach to relieving energy shortages.Carbon quantum dots(CQDs) have shown distinct properties and attracted tremendous interest in CO2 reduction.Herein,we report a joint experimental-computational mechanistic study of photoreduction CO2 to CO on the model catalyst 9-hydroxyphenal-1-one(HPHN) CQDs with known structure.Our theoretical calculations reveal that the rate-determining step is COOH·formation,which is closely related to the proton and electron transfer induced by hydrogen bonding in the excited state.According to the calculated volcano plot,the solution we proposed is addition Zn^(2+) ions.The active center changed from the hydroxyl oxygen atom to the Zn atom and the barrier of the COOH·formation step is noticeably decreased when Zn^(2+) ions are added.It is further confirmed by the experimental data that the activity of CO2 reduction increases 2.9 times when Zn^(2+) ions are added.
基金This work was financially supported by the National Key Research and Development Program of China(2018YFA0702002)the Beijing Natural Science Foundation(Z210016)+1 种基金the National Natural Science Foundation of China(51967020,21935001)Shanxi Energy Internet Research Institute(SXEI 2023A004).
文摘The exploration of sustainable energy utilization requires the imple-mentation of advanced electrochemical devices for efficient energy conversion and storage,which are enabled by the usage of cost-effective,high-performance electro-catalysts.Currently,heterogeneous atomically dispersed catalysts are considered as potential candidates for a wide range of applications.Compared to conventional cata-lysts,atomically dispersed metal atoms in carbon-based catalysts have more unsatu-rated coordination sites,quantum size effect,and strong metal-support interactions,resulting in exceptional catalytic activity.Of these,dual-atomic catalysts(DACs)have attracted extensive attention due to the additional synergistic effect between two adja-cent metal atoms.DACs have the advantages of full active site exposure,high selectiv-ity,theoretical 100%atom utilization,and the ability to break the scaling relationship of adsorption free energy on active sites.In this review,we summarize recent research advancement of DACs,which includes(1)the comprehensive understanding of the synergy between atomic pairs;(2)the synthesis of DACs;(3)characterization meth-ods,especially aberration-corrected scanning transmission electron microscopy and synchrotron spectroscopy;and(4)electrochemical energy-related applications.The last part focuses on great potential for the electrochemical catalysis of energy-related small molecules,such as oxygen reduction reaction,CO_(2) reduction reaction,hydrogen evolution reaction,and N_(2) reduction reaction.The future research challenges and opportunities are also raised in prospective section.