Global investment in ethylene(C_(2)H_(4))production via nonpetroleum pathways is rising,highlighting its growing importance in the energy and environmental sectors.The electroreduction of carbon dioxide(CO_(2))to C_(2...Global investment in ethylene(C_(2)H_(4))production via nonpetroleum pathways is rising,highlighting its growing importance in the energy and environmental sectors.The electroreduction of carbon dioxide(CO_(2))to C_(2)H_(4) inflow cells is emerging as a promising technology with broad practical applications.Direct delivery of gaseous CO_(2) to the cathode catalyst layer overcomes mass transfer limitations,enhancing reaction rates and enabling high current density.This review summarizes recent research progress in the electrocatalytic CO_(2) reduction reaction(eCO_(2)RR)for selective C_(2)H_(4) production inflow cells.It outlines the principles of eCO_(2)RR to C_(2)H_(4) and discusses the influence of copper-based catalyst morphology,crystal facet,oxidation state,surface modification strategy,and synergistic effects on catalytic performance.In addition,it highlights the compositional structure of theflow cell,and the selection and optimization of operating conditions,including gas diffusion electrodes,electrolytes,ion exchange membranes,and alternative anode reaction types beyond the oxygen evolution reaction.Finally,advances in machine learning are presented for accelerating catalyst screening and predicting dynamic changes in catalysts during reduction.This comprehensive review serves as a valuable reference for the development of efficient catalysts and the construction of electrolytic devices for the electrocatalytic reduction of CO_(2) to C_(2)H_(4).展开更多
Photocatalytic synthesis of hydrogen peroxide(H_(2)O_(2))has emerged as a promising approach because of its simplicity and environmental benefits.However,significant challenges remain obstacles to their advancement,su...Photocatalytic synthesis of hydrogen peroxide(H_(2)O_(2))has emerged as a promising approach because of its simplicity and environmental benefits.However,significant challenges remain obstacles to their advancement,such as the rapid recombination of photogenerated charge carriers and sluggish surface redox reactions on nonmetallic organic catalysts.Metal-based organic catalysts with tunable electronic structures are considered ideal for exploring the mechanisms and structure-performance relationships in H_(2)O_(2) synthesis.This review summarizes the fundamental principles of photocatalytic H_(2)O_(2) synthesis via oxygen reduction and water oxidation reactions.Recent advancements in electronic structure tuning strategies for metal-based organic catalysts are critically examined,focusing on their impact on light absorption range,photogenerated carrier separation,O_(2) activation,and the selective generation of H_(2)O_(2).In addition,this review comprehensively evaluates the applications of sacrificial agents in photocatalytic reaction systems and offers insights into the future development of metal-based organic catalysts for H_(2)O_(2) photosynthesis.展开更多
The development of a selective catalyst for the conversion of biomass and plastics into H2by steam reforming can combat the energy crisis and global warming.In this work,support Ni-Fe-Ca/H-Al bifunctional catalysts we...The development of a selective catalyst for the conversion of biomass and plastics into H2by steam reforming can combat the energy crisis and global warming.In this work,support Ni-Fe-Ca/H-Al bifunctional catalysts were prepared by loading Ni and Fe into pretreatment CaO/Al_(2)O_(3)(Ca/H-Al)carriers and showed high catalytic activity for the steam reforming of biomass and plastic.Moreover,the idea of bidirectional degradation was exploited to strengthen the pyrolysis of plastic with a high H/C and biomass with a high O/C.Interestingly,the products presented high H2selective(1302.10 m L/g)and low CO_(2)yield(120.23 m L/g)in 7Ni-5Fe-Ca/H-Al(2:4)catalyst compared with current reports.Here,the abundant oxygen vacancies(Ov)in the H-Al carrier exhibited an electron-deficient nature,providing active sites for anchoring Ni O.Meanwhile,Ni O interacted with Ca_(2)Fe_(2)O_(5)to produce more defective Ovsites,which stabilized the NiO particles in the 7Ni-5Fe-Ca/H-Al(2:4)catalyst,and the interaction between the catalyst and the carrier was enhanced,leading to the reduction of weakly basic sites,this property promoted the strong adsorption of CO_(2)and H2O by the catalyst,contributing to the enhancement of efficient steam conversion and the promotion of conversion of by-products to H2.Notably,7Ni-5Fe-Ca/H-Al(2:4)catalysts maintained structural integrity after regeneration and exhibited excellent regenerability in H2selection and CO_(2)adsorption.The work provides a new idea for the study of efficient H2production from steam reforming of biomass and plastics.展开更多
Solar‐powered semiconductor photocatalysis is considered a powerful strategy for addressing environmental pollution and energy crisis.Nevertheless,the separation and transfer abilities of photogenerated photocatalyst...Solar‐powered semiconductor photocatalysis is considered a powerful strategy for addressing environmental pollution and energy crisis.Nevertheless,the separation and transfer abilities of photogenerated photocatalysts remain unsatisfactory.Herein,dual Ti_(3)C_(2)nanosheets/Ag co‐catalysts synergistically decorated hierarchical flower‐like TiO_(2)microspheres for boosting photocatalytic H_(2)production were fabricated by electrostatic self‐assembly and subsequent photoreduction procedures.The optimal Ag/Ti_(3)C_(2)/TiO_(2)composite demonstrated an excellent photocatalytic H_(2)‐production rate of 1024.72μmol g^(−1)h^(−1)under simulated solar irradiation,achieving nearly 40,2.3,and 1.8 folds with respect to that obtained on pristine TiO2,optimized Ti_(3)C_(2)/TiO_(2)composite,and Ag/TiO_(2)composite,respectively.The considerably improved photocatalytic H_(2)‐production activity is associated with the synergistic effect of the hierarchical flower‐like structure of TiO2,excellent electrical conductivity of Ti_(3)C_(2),and surface plasmon resonance effect of Ag,which enhances the light absorption capacity and promotes the separation and transfer of photogenerated carriers.This study provides insight into the design of high‐efficiency photocatalysts with dual co‐catalysts for solar H_(2)production.展开更多
H_(2)S selective catalytic oxidation technology is a prospective way for the treatment of low concentration acid gas with simple process operation and low investment. However, undesirable results such as large formati...H_(2)S selective catalytic oxidation technology is a prospective way for the treatment of low concentration acid gas with simple process operation and low investment. However, undesirable results such as large formation of SO_(2) and catalyst deactivation inevitably occur, due to the temperature rise of fixed reaction bed caused by the exothermic reaction. Catalyst with high activity in wide operating temperature window, especially in high temperature range, is urgently needed. In this paper, a series of copper-substituted hexaaluminate catalysts (LaCu_(x), x = 0, 0.5, 1, 1.5, 2, 2.5) were prepared and investigated for the H_(2)S selective oxidation reaction at high temperature conditions (300-550℃). The LaCu_(1) catalyst exhibited excellent catalytic performance and great stability, which was attributed to the best reductive properties and proper pore structure. Besides, two facile deep processing paths were proposed to eliminate the remaining H_(2)S and SO_(2) in the tail gas.展开更多
Effective charge separation and rapid interfacial H_(2) production are imperative for the construction of efficient photocatalysts.Compared to Pt,the metallic Ag co‐catalyst with its strong electron‐trapping ability...Effective charge separation and rapid interfacial H_(2) production are imperative for the construction of efficient photocatalysts.Compared to Pt,the metallic Ag co‐catalyst with its strong electron‐trapping ability and excellent electronic conductivity typically exhibits an extremely limited photocatalytic H_(2-)evolution rate owing to its sluggish interfacial H_(2)‐generation reaction.In this study,amorphous AgSe_(x) was incorporated in situ onto metallic Ag as a novel and excellent H_(2)‐evolution active site to boost the interfacial H_(2)‐generation rate of Ag nanoparticles in a TiO_(2)/Ag system.Core‐shell Ag@AgSe_(x)nanoparticle‐modified TiO_(2)photocatalysts were prepared via a two‐step pathway involving the photodeposition of metallic Ag and the selective surface selenization of metallic Ag to yield amorphous AgSe_(x)shells.The as‐prepared TiO_(2)/Ag@AgSe_(x)(20μL)photocatalyst exhibited an excellent H_(2‐)production performance of 853.0μmol h^(-1)g^(-1),prominently outperforming the TiO_(2)and TiO_(2)/Ag samples by factors of 11.6 and 2.4,respectively.Experimental investigations and DFT calculations revealed that the enhanced H_(2‐)generation activity of the TiO_(2)/Ag@AgSe_(x)photocatalyst could be accounted by synergistic interactions of the Ag@AgSe_(x)co‐catalyst.Essentially,the metallic Ag core could quickly capture and transport the photoinduced electrons from TiO_(2)to the amorphous AgSe_(x)shell,whereas the amorphous AgSe_(x)shell provided large active sites for boosting the interfacial H_(2)evolution.This study offers a facile route for the construction of novel core‐shell co‐catalysts for sustainable H_(2)evolution.展开更多
In this work,to study the phase structure effect,three groups of Cu/REO catalysts were prepared with cubic and monoclinic Gd_(2)O_(3),Eu_(2)O_(3)and Sm_(2)O_(3) supports for MSR reaction to produce H_(2).Based on CH3O...In this work,to study the phase structure effect,three groups of Cu/REO catalysts were prepared with cubic and monoclinic Gd_(2)O_(3),Eu_(2)O_(3)and Sm_(2)O_(3) supports for MSR reaction to produce H_(2).Based on CH3OH conversion and H_(2)yield,the reaction perfo rmance of the catalysts ranks as Cu/Sm_(2)O_(3)-M>Cu/Sm_(2)O_(3)-C>Cu/Gd_(2)O_(3)-M>Cu/Gd_(2)O_(3)-C>Cu/Eu_(2)O_(3)-M>Cu/Eu_(2)O_(3)-C.For the same kind of REO,Cu supported on the monoclinic support shows better performance than on the cubic one.Despite the phase structure difference,Sm_(2)O_(3) is the best support among all the three kinds of REOs.Compared with Cu/REO catalysts prepared with cubic supports,the corresponding catalysts prepared with monoclinic supports generally possess mo re surface oxygen vacancies,which can generate mo re surface active oxygen(O_(2)^(-)) and moderate basic sites.Moreover,the contents of Cu^(+) on the catalysts follow the same sequence.The reaction performance is positively related to the amount of these three types of surface sites.But metallic Cuo species is necessary to maintain the Cu^(+)■Cu^(0) redox cycle.Furthe rmore,on a catalyst with good perfo rmance,those vital surface reaction intermediates can be stabilized during the reaction.Cu/Sm_(2)O_(3)-M possesses the largest quantities of these surface sites,and has the appropriate amount of Cu^(+) and Cu^(0) after reduction,thereby displaying the optimal performance in all the catalysts.In conclusion,evident support crystal structure effect is observed for Cu/REO catalysts,and a monoclinic phase REO is a better support than the respective cubic phase one.展开更多
In the field of catalytic hydro-genation,two primary mecha-nistic pathways,namely the Ho-riuti-Polanyi(HP)mechanism and the non-HP mechanism,have been extensively investi-gated.Current understandings suggested that th...In the field of catalytic hydro-genation,two primary mecha-nistic pathways,namely the Ho-riuti-Polanyi(HP)mechanism and the non-HP mechanism,have been extensively investi-gated.Current understandings suggested that the non-HP mechanism preferred to occur on the coinage metal surfaces,such as copper,silver,and gold,which exhibited low activity towards H_(2) dissociation.Herein,we offered a detailed theoretical investigation into the mechanisms of CO_(2)hydrogenation to formic acid on M_(1)-In_(2)O_(3)(111)surfaces,using density functional theory calculations.Our calculations provided novel in-sights into the preference of the non-HP mechanism on reduced single-atom noble metal cata-lysts,such as r-Rh_(1)-In_(2)O_(3)(111)and r-Ir_(1)-In_(2)O_(3)(111).In these cases,molecularly adsorbed H_(2) would be polarized into H^(δ−)-H^(δ+),thus facilitating the electrophilic attack to the O in CO_(2).Conversely,the H^(δ+)species,derived from heterolytically dissociated H_(2),exhibited a strong affinity on the adjacent oxygen site at the M-O-In interface.This strong adsorption resulted in a higher energy barrier for CO_(2)hydrogenation,thereby rendering the HP mechanism less viable than the non-HP one.Our results were anticipated to provide a deeper understanding of hydrogenation reactions on oxide-supported noble single-atom catalysts and theoretical guidance for the development of novel high-performance catalysts for catalytic hydrogena-tion reactions.展开更多
Ethanol steam reforming(ESR)represents a promising route for sustainable hydrogen production,leveraging the high hydrogen content,renewability,and logistical advantages of ethanol.Although Ni-based catalysts are leadi...Ethanol steam reforming(ESR)represents a promising route for sustainable hydrogen production,leveraging the high hydrogen content,renewability,and logistical advantages of ethanol.Although Ni-based catalysts are leading non-noble candidates for ESR,their practical deployment is hindered by compromised H_(2) production efficiency and rapid deactivation.In this work,we combined catalyst synthesis,kinetic analysis,and mechanistic investigation to elucidate the effectsof Ni particle size(3-9 nm)on ESR performance of Ni/CeO_(2) catalysts.These Ni/CeO_(2) catalysts were prepared via a citric acid-assisted coprecipitation method,and systematically characterized using complementary techniques,including high-resolution transmission electron microscopy(HRTEM),in situ X-ray photoelectron spectroscopy(XPS),hydrogen temperature-programmed reduction(H_(2)-TPR),Raman spectroscopy,O_(2)/CO chemisorption,and temperature-programmed surface reaction(TPSR)analyses.Mechanistic study revealed that ethanol dehydrogenation to acetaldehyde is the rate-determining step,defining the intrinsic activity of Ni sites,whereas C-C bond cleavage governs H_(2) selectivity in ESR.At smaller Ni sizes(e.g.,3.1 nm),larger CeO_(2) surface was exposed,which promoted acetaldehyde condensation to acetone,and consequently reduced H_(2) production efficiency.The Ni/CeO_(2) catalyst with~5 nm of Ni particles afforded the highest H_(2) yield(66.3%)and outstanding stability by balancing dehydrogenation activity,H_(2) selectivity,and coking resistance.Conversely,larger Ni particles(>6 nm)facilitated methanation reaction and catalyst deactivation.This work reconciles prior inconsistencies in the Ni size effects on ESR and provides guidance for the design of efficient and durable Ni-based catalysts for H_(2) production.展开更多
The reduction of carbon emissions in the steel industry is a significant challenge,and utilizing CO_(2) from carbon intensive steel industry off-gases for methanol production is a promising strategy for decarbonizatio...The reduction of carbon emissions in the steel industry is a significant challenge,and utilizing CO_(2) from carbon intensive steel industry off-gases for methanol production is a promising strategy for decarbonization.However,steelwork off-gases typically contain various impurities,including H_(2)S,which can deactivate commercial methanol synthesis catalysts,Cu/ZnO/Al_(2)O_(3)(CZA).Reverse water-gas shift(RWGS)reaction is the predominant side reaction in CO_(2) hydrogenation to methanol which can occur at ambient pressure,enabling the decouple of RWGS from methanol production at high pressure.Then,a series of activated CZA catalysts has been in-situ pretreated in 400 ppm H_(2)S/Ar at 250℃and tested for both RWGS reaction at ambient pressure and CO_(2) hydrogenation to methanol at high pressure.An innovative decoupling strategy was employed to isolate the RWGS reaction from the methanol synthesis process,enabling the investigation of the evolution of active site structures and the poisoning mechanism through elemental analysis,X-ray Diffraction,X-ray Photoelectron Spectroscopy,Fourier Transform Infrared Spectroscopy,Temperature Programmed Reduction and CO_(2) Temperature Programmed Desorption.The results indicate that there are different dynamic migration behaviors of ZnO_(x) in the two reaction systems,leading to different poisoning mechanisms.These interesting findings are beneficial to develop sulfur resistant and durable highly efficient catalysts for CO_(2) hydrogenation to methanol,promoting the carbon emission reduction in steel industry.展开更多
Herein,we report a highly active K-added Ru/MgO catalyst for hydrogen storage into aromatic benzyltoluenes at low temperatures to advance liquid organic hydrogen carrier technology.The hydrogenation activity of Ru/K/M...Herein,we report a highly active K-added Ru/MgO catalyst for hydrogen storage into aromatic benzyltoluenes at low temperatures to advance liquid organic hydrogen carrier technology.The hydrogenation activity of Ru/K/MgO catalysts exhibits a volcano-shaped dependence on the K content at the maximum with 0.02 wt%.This is in good agreement with the strength and capacity of H_(2) adsorption derived from basicity,despite a gradual decrease in the textural property and the corresponding increase in the Ru particle size with increasing the K content.Density functional theory calculations show that heterolytic hydrogen adsorption properties(strength and polarization)are facilitated up to a specific density of K on the Ru–MgO interface and excessive K suppresses heterolytic H_(2) adsorption by direct interaction between K and hydrogen,assuring the hydrogenation activity and H_(2) adsorption capability of Ru/K/MgO catalysts.Hence,the Ru/K/MgO catalyst,when K is added in an optimal amount,is highly effective to accelerate hydrogen storage kinetics at low temperatures owing to the enhanced heterolytic H_(2) adsorption.展开更多
Several supported zirconocene catalysts were prepared by using MgCl_2·6H_2O as a precursor forproducing an active support. Such catalysts combined with methylaluminoxane (MAO) obtained by reactingMgCl_2·6H_2...Several supported zirconocene catalysts were prepared by using MgCl_2·6H_2O as a precursor forproducing an active support. Such catalysts combined with methylaluminoxane (MAO) obtained by reactingMgCl_2·6H_2O with AlMe_3 show good activity for ethylene polymerization similar to that of anhydrousMgCl_2 supported zirconocene catalyst.展开更多
基金supported by the National Natural Science Foundation of China(22272081 and 51802160)the Startup Foundation for Introducing Talent of NUIST(S8113082001).
文摘Global investment in ethylene(C_(2)H_(4))production via nonpetroleum pathways is rising,highlighting its growing importance in the energy and environmental sectors.The electroreduction of carbon dioxide(CO_(2))to C_(2)H_(4) inflow cells is emerging as a promising technology with broad practical applications.Direct delivery of gaseous CO_(2) to the cathode catalyst layer overcomes mass transfer limitations,enhancing reaction rates and enabling high current density.This review summarizes recent research progress in the electrocatalytic CO_(2) reduction reaction(eCO_(2)RR)for selective C_(2)H_(4) production inflow cells.It outlines the principles of eCO_(2)RR to C_(2)H_(4) and discusses the influence of copper-based catalyst morphology,crystal facet,oxidation state,surface modification strategy,and synergistic effects on catalytic performance.In addition,it highlights the compositional structure of theflow cell,and the selection and optimization of operating conditions,including gas diffusion electrodes,electrolytes,ion exchange membranes,and alternative anode reaction types beyond the oxygen evolution reaction.Finally,advances in machine learning are presented for accelerating catalyst screening and predicting dynamic changes in catalysts during reduction.This comprehensive review serves as a valuable reference for the development of efficient catalysts and the construction of electrolytic devices for the electrocatalytic reduction of CO_(2) to C_(2)H_(4).
文摘Photocatalytic synthesis of hydrogen peroxide(H_(2)O_(2))has emerged as a promising approach because of its simplicity and environmental benefits.However,significant challenges remain obstacles to their advancement,such as the rapid recombination of photogenerated charge carriers and sluggish surface redox reactions on nonmetallic organic catalysts.Metal-based organic catalysts with tunable electronic structures are considered ideal for exploring the mechanisms and structure-performance relationships in H_(2)O_(2) synthesis.This review summarizes the fundamental principles of photocatalytic H_(2)O_(2) synthesis via oxygen reduction and water oxidation reactions.Recent advancements in electronic structure tuning strategies for metal-based organic catalysts are critically examined,focusing on their impact on light absorption range,photogenerated carrier separation,O_(2) activation,and the selective generation of H_(2)O_(2).In addition,this review comprehensively evaluates the applications of sacrificial agents in photocatalytic reaction systems and offers insights into the future development of metal-based organic catalysts for H_(2)O_(2) photosynthesis.
基金the National Natural Science of China(21968037)the Reserve Program for Young and Middle-aged Academic and Technical Leaders in Yunnan Province(202205AC160031)+1 种基金the Research Innovation Project of Yunnan University for Graduate Students on Exemption,the Highlevel Talent Promotion and Training Project of Kunming(2022SCP003)advanced analysis and measurement center of Yunnan university for the sample testing service。
文摘The development of a selective catalyst for the conversion of biomass and plastics into H2by steam reforming can combat the energy crisis and global warming.In this work,support Ni-Fe-Ca/H-Al bifunctional catalysts were prepared by loading Ni and Fe into pretreatment CaO/Al_(2)O_(3)(Ca/H-Al)carriers and showed high catalytic activity for the steam reforming of biomass and plastic.Moreover,the idea of bidirectional degradation was exploited to strengthen the pyrolysis of plastic with a high H/C and biomass with a high O/C.Interestingly,the products presented high H2selective(1302.10 m L/g)and low CO_(2)yield(120.23 m L/g)in 7Ni-5Fe-Ca/H-Al(2:4)catalyst compared with current reports.Here,the abundant oxygen vacancies(Ov)in the H-Al carrier exhibited an electron-deficient nature,providing active sites for anchoring Ni O.Meanwhile,Ni O interacted with Ca_(2)Fe_(2)O_(5)to produce more defective Ovsites,which stabilized the NiO particles in the 7Ni-5Fe-Ca/H-Al(2:4)catalyst,and the interaction between the catalyst and the carrier was enhanced,leading to the reduction of weakly basic sites,this property promoted the strong adsorption of CO_(2)and H2O by the catalyst,contributing to the enhancement of efficient steam conversion and the promotion of conversion of by-products to H2.Notably,7Ni-5Fe-Ca/H-Al(2:4)catalysts maintained structural integrity after regeneration and exhibited excellent regenerability in H2selection and CO_(2)adsorption.The work provides a new idea for the study of efficient H2production from steam reforming of biomass and plastics.
文摘Solar‐powered semiconductor photocatalysis is considered a powerful strategy for addressing environmental pollution and energy crisis.Nevertheless,the separation and transfer abilities of photogenerated photocatalysts remain unsatisfactory.Herein,dual Ti_(3)C_(2)nanosheets/Ag co‐catalysts synergistically decorated hierarchical flower‐like TiO_(2)microspheres for boosting photocatalytic H_(2)production were fabricated by electrostatic self‐assembly and subsequent photoreduction procedures.The optimal Ag/Ti_(3)C_(2)/TiO_(2)composite demonstrated an excellent photocatalytic H_(2)‐production rate of 1024.72μmol g^(−1)h^(−1)under simulated solar irradiation,achieving nearly 40,2.3,and 1.8 folds with respect to that obtained on pristine TiO2,optimized Ti_(3)C_(2)/TiO_(2)composite,and Ag/TiO_(2)composite,respectively.The considerably improved photocatalytic H_(2)‐production activity is associated with the synergistic effect of the hierarchical flower‐like structure of TiO2,excellent electrical conductivity of Ti_(3)C_(2),and surface plasmon resonance effect of Ag,which enhances the light absorption capacity and promotes the separation and transfer of photogenerated carriers.This study provides insight into the design of high‐efficiency photocatalysts with dual co‐catalysts for solar H_(2)production.
基金financially supported by the National Natural Science Foundation of China (Nos. 21976176, 22006148)the Key R&D Program of Shandong province (No. 2019JZZY010506)the Fundamental Research Funds for the Central Universities。
文摘H_(2)S selective catalytic oxidation technology is a prospective way for the treatment of low concentration acid gas with simple process operation and low investment. However, undesirable results such as large formation of SO_(2) and catalyst deactivation inevitably occur, due to the temperature rise of fixed reaction bed caused by the exothermic reaction. Catalyst with high activity in wide operating temperature window, especially in high temperature range, is urgently needed. In this paper, a series of copper-substituted hexaaluminate catalysts (LaCu_(x), x = 0, 0.5, 1, 1.5, 2, 2.5) were prepared and investigated for the H_(2)S selective oxidation reaction at high temperature conditions (300-550℃). The LaCu_(1) catalyst exhibited excellent catalytic performance and great stability, which was attributed to the best reductive properties and proper pore structure. Besides, two facile deep processing paths were proposed to eliminate the remaining H_(2)S and SO_(2) in the tail gas.
文摘Effective charge separation and rapid interfacial H_(2) production are imperative for the construction of efficient photocatalysts.Compared to Pt,the metallic Ag co‐catalyst with its strong electron‐trapping ability and excellent electronic conductivity typically exhibits an extremely limited photocatalytic H_(2-)evolution rate owing to its sluggish interfacial H_(2)‐generation reaction.In this study,amorphous AgSe_(x) was incorporated in situ onto metallic Ag as a novel and excellent H_(2)‐evolution active site to boost the interfacial H_(2)‐generation rate of Ag nanoparticles in a TiO_(2)/Ag system.Core‐shell Ag@AgSe_(x)nanoparticle‐modified TiO_(2)photocatalysts were prepared via a two‐step pathway involving the photodeposition of metallic Ag and the selective surface selenization of metallic Ag to yield amorphous AgSe_(x)shells.The as‐prepared TiO_(2)/Ag@AgSe_(x)(20μL)photocatalyst exhibited an excellent H_(2‐)production performance of 853.0μmol h^(-1)g^(-1),prominently outperforming the TiO_(2)and TiO_(2)/Ag samples by factors of 11.6 and 2.4,respectively.Experimental investigations and DFT calculations revealed that the enhanced H_(2‐)generation activity of the TiO_(2)/Ag@AgSe_(x)photocatalyst could be accounted by synergistic interactions of the Ag@AgSe_(x)co‐catalyst.Essentially,the metallic Ag core could quickly capture and transport the photoinduced electrons from TiO_(2)to the amorphous AgSe_(x)shell,whereas the amorphous AgSe_(x)shell provided large active sites for boosting the interfacial H_(2)evolution.This study offers a facile route for the construction of novel core‐shell co‐catalysts for sustainable H_(2)evolution.
基金Project supported by the National Natural Science Foundation of China(22172071,22102069,22062013,22262021,21962009)Natural Science Foundation of Jiangxi Province,China(20202BAB203006,20212BAB203030)Key Laboratory Foundation of Jiangxi Province for Environment and Energy Catalysis,China(20181BCD40004).
文摘In this work,to study the phase structure effect,three groups of Cu/REO catalysts were prepared with cubic and monoclinic Gd_(2)O_(3),Eu_(2)O_(3)and Sm_(2)O_(3) supports for MSR reaction to produce H_(2).Based on CH3OH conversion and H_(2)yield,the reaction perfo rmance of the catalysts ranks as Cu/Sm_(2)O_(3)-M>Cu/Sm_(2)O_(3)-C>Cu/Gd_(2)O_(3)-M>Cu/Gd_(2)O_(3)-C>Cu/Eu_(2)O_(3)-M>Cu/Eu_(2)O_(3)-C.For the same kind of REO,Cu supported on the monoclinic support shows better performance than on the cubic one.Despite the phase structure difference,Sm_(2)O_(3) is the best support among all the three kinds of REOs.Compared with Cu/REO catalysts prepared with cubic supports,the corresponding catalysts prepared with monoclinic supports generally possess mo re surface oxygen vacancies,which can generate mo re surface active oxygen(O_(2)^(-)) and moderate basic sites.Moreover,the contents of Cu^(+) on the catalysts follow the same sequence.The reaction performance is positively related to the amount of these three types of surface sites.But metallic Cuo species is necessary to maintain the Cu^(+)■Cu^(0) redox cycle.Furthe rmore,on a catalyst with good perfo rmance,those vital surface reaction intermediates can be stabilized during the reaction.Cu/Sm_(2)O_(3)-M possesses the largest quantities of these surface sites,and has the appropriate amount of Cu^(+) and Cu^(0) after reduction,thereby displaying the optimal performance in all the catalysts.In conclusion,evident support crystal structure effect is observed for Cu/REO catalysts,and a monoclinic phase REO is a better support than the respective cubic phase one.
基金supported by the National Key Research and Development Program of Ministry of Sci-ence and Technology of China(No.2022YFA1504601)the National Natural Science Foundation of China(Nos.92045303,22132004,22121001,22072116,22072117,and 21773192).
文摘In the field of catalytic hydro-genation,two primary mecha-nistic pathways,namely the Ho-riuti-Polanyi(HP)mechanism and the non-HP mechanism,have been extensively investi-gated.Current understandings suggested that the non-HP mechanism preferred to occur on the coinage metal surfaces,such as copper,silver,and gold,which exhibited low activity towards H_(2) dissociation.Herein,we offered a detailed theoretical investigation into the mechanisms of CO_(2)hydrogenation to formic acid on M_(1)-In_(2)O_(3)(111)surfaces,using density functional theory calculations.Our calculations provided novel in-sights into the preference of the non-HP mechanism on reduced single-atom noble metal cata-lysts,such as r-Rh_(1)-In_(2)O_(3)(111)and r-Ir_(1)-In_(2)O_(3)(111).In these cases,molecularly adsorbed H_(2) would be polarized into H^(δ−)-H^(δ+),thus facilitating the electrophilic attack to the O in CO_(2).Conversely,the H^(δ+)species,derived from heterolytically dissociated H_(2),exhibited a strong affinity on the adjacent oxygen site at the M-O-In interface.This strong adsorption resulted in a higher energy barrier for CO_(2)hydrogenation,thereby rendering the HP mechanism less viable than the non-HP one.Our results were anticipated to provide a deeper understanding of hydrogenation reactions on oxide-supported noble single-atom catalysts and theoretical guidance for the development of novel high-performance catalysts for catalytic hydrogena-tion reactions.
基金supported by the National Key Research and Develop-ment Pr0gram of China(Nos.2021YFA1501104 and 2023YFA1506802)the National Natural Science Foundation of China(No.22032001).
文摘Ethanol steam reforming(ESR)represents a promising route for sustainable hydrogen production,leveraging the high hydrogen content,renewability,and logistical advantages of ethanol.Although Ni-based catalysts are leading non-noble candidates for ESR,their practical deployment is hindered by compromised H_(2) production efficiency and rapid deactivation.In this work,we combined catalyst synthesis,kinetic analysis,and mechanistic investigation to elucidate the effectsof Ni particle size(3-9 nm)on ESR performance of Ni/CeO_(2) catalysts.These Ni/CeO_(2) catalysts were prepared via a citric acid-assisted coprecipitation method,and systematically characterized using complementary techniques,including high-resolution transmission electron microscopy(HRTEM),in situ X-ray photoelectron spectroscopy(XPS),hydrogen temperature-programmed reduction(H_(2)-TPR),Raman spectroscopy,O_(2)/CO chemisorption,and temperature-programmed surface reaction(TPSR)analyses.Mechanistic study revealed that ethanol dehydrogenation to acetaldehyde is the rate-determining step,defining the intrinsic activity of Ni sites,whereas C-C bond cleavage governs H_(2) selectivity in ESR.At smaller Ni sizes(e.g.,3.1 nm),larger CeO_(2) surface was exposed,which promoted acetaldehyde condensation to acetone,and consequently reduced H_(2) production efficiency.The Ni/CeO_(2) catalyst with~5 nm of Ni particles afforded the highest H_(2) yield(66.3%)and outstanding stability by balancing dehydrogenation activity,H_(2) selectivity,and coking resistance.Conversely,larger Ni particles(>6 nm)facilitated methanation reaction and catalyst deactivation.This work reconciles prior inconsistencies in the Ni size effects on ESR and provides guidance for the design of efficient and durable Ni-based catalysts for H_(2) production.
基金supported by the National Natural Science Foundation of China(Nos.22276060 and 21976059)Guangdong Basic and Applied Basic Research Foundation(No.2024A1515012636)China Scholarship Council Scholarship(No.201906155006)。
文摘The reduction of carbon emissions in the steel industry is a significant challenge,and utilizing CO_(2) from carbon intensive steel industry off-gases for methanol production is a promising strategy for decarbonization.However,steelwork off-gases typically contain various impurities,including H_(2)S,which can deactivate commercial methanol synthesis catalysts,Cu/ZnO/Al_(2)O_(3)(CZA).Reverse water-gas shift(RWGS)reaction is the predominant side reaction in CO_(2) hydrogenation to methanol which can occur at ambient pressure,enabling the decouple of RWGS from methanol production at high pressure.Then,a series of activated CZA catalysts has been in-situ pretreated in 400 ppm H_(2)S/Ar at 250℃and tested for both RWGS reaction at ambient pressure and CO_(2) hydrogenation to methanol at high pressure.An innovative decoupling strategy was employed to isolate the RWGS reaction from the methanol synthesis process,enabling the investigation of the evolution of active site structures and the poisoning mechanism through elemental analysis,X-ray Diffraction,X-ray Photoelectron Spectroscopy,Fourier Transform Infrared Spectroscopy,Temperature Programmed Reduction and CO_(2) Temperature Programmed Desorption.The results indicate that there are different dynamic migration behaviors of ZnO_(x) in the two reaction systems,leading to different poisoning mechanisms.These interesting findings are beneficial to develop sulfur resistant and durable highly efficient catalysts for CO_(2) hydrogenation to methanol,promoting the carbon emission reduction in steel industry.
基金financially supported by the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT,Republic of Korea(2019M3E6A1064908)the Ministry of Education,Republic of Korea(2016R1A6A1A03013422)。
文摘Herein,we report a highly active K-added Ru/MgO catalyst for hydrogen storage into aromatic benzyltoluenes at low temperatures to advance liquid organic hydrogen carrier technology.The hydrogenation activity of Ru/K/MgO catalysts exhibits a volcano-shaped dependence on the K content at the maximum with 0.02 wt%.This is in good agreement with the strength and capacity of H_(2) adsorption derived from basicity,despite a gradual decrease in the textural property and the corresponding increase in the Ru particle size with increasing the K content.Density functional theory calculations show that heterolytic hydrogen adsorption properties(strength and polarization)are facilitated up to a specific density of K on the Ru–MgO interface and excessive K suppresses heterolytic H_(2) adsorption by direct interaction between K and hydrogen,assuring the hydrogenation activity and H_(2) adsorption capability of Ru/K/MgO catalysts.Hence,the Ru/K/MgO catalyst,when K is added in an optimal amount,is highly effective to accelerate hydrogen storage kinetics at low temperatures owing to the enhanced heterolytic H_(2) adsorption.
文摘Several supported zirconocene catalysts were prepared by using MgCl_2·6H_2O as a precursor forproducing an active support. Such catalysts combined with methylaluminoxane (MAO) obtained by reactingMgCl_2·6H_2O with AlMe_3 show good activity for ethylene polymerization similar to that of anhydrousMgCl_2 supported zirconocene catalyst.
