The facet effect of metal-organic frameworks(MOF)on regulating the property of loaded co-catalysts is an important but unexplored issue in the field of photocatalysis.In this work,a series of MIL-125-NH_(2)polyhedrons...The facet effect of metal-organic frameworks(MOF)on regulating the property of loaded co-catalysts is an important but unexplored issue in the field of photocatalysis.In this work,a series of MIL-125-NH_(2)polyhedrons(MIL=Materials Institute Lavoisier)with facet exposure of{001},{001}/{111}and{111}are synthesized and used to load Pd-based co-catalysts for photocatalytic oxygen reduction reaction(ORR)toward H_(2)O_(2)production.The different facets with distinct chemical environments(Ti-O clusters on{111}facets and carboxyl ligands on{001}facets)result in the selective loading of Pd0and PdO dominated cocatalysts on{001}and{111}facets,respectively.The{001}/{111}co-exposed MIL-125-NH_(2)thus enables the spatially separated loading of Pd0and Pd O dual cocatalysts respectively.Pd0efficiently traps the photoexcited electrons and PdO trends to capture the holes,collaboratively promoting the directional separation of photogenerated electron-hole pairs.As a result,the photocatalytic ORR activity is significantly enhanced with a H_(2)O_(2)production rate of 128.6 mmol L^(-1)g^(-1)h^(-1),superior than pristine and single cocatalyst modified MIL-125-NH_(2)samples.Our findings provide new insight into the design of high-performance photocatalysts.展开更多
The electrochemical hydrogenation of HMF to BHMF is an elegant alternative to the conventio nal thermocatalytic route for the production of high-value-added chemicals from biomass resources.In virtue of the wide poten...The electrochemical hydrogenation of HMF to BHMF is an elegant alternative to the conventio nal thermocatalytic route for the production of high-value-added chemicals from biomass resources.In virtue of the wide potential window with promising Faradic efficiency(FE) towards BHMF,Cu-based electrode has been in the center of investigation.However,its structure-activity relationship remains ambiguous and its intrinsic catalytic activity is still unsatisfactory.In this work,we develop a two-step oxidation-reduction strategy to reconstruct the surface atom arrangement of the Cu foam(CF).By combination of multiple quasi-situ/in-situ techniques and density functional theory(DFT) calculation,the critical factor that governs the reaction is demonstrated to be facet effect of the metallic Cu crystal:Cu(110) facet accounts for the most favorable surface with enhanced chemisorption with reactants and selective production of BHMF,while Cu(100) facet might trigger the accumulation of the by-product 5,5'-bis(hydroxy methy)hydrofurion(BHH).With the optimized composition of the facets on the reconstructed Cu(OH)_(2)-ER/CF,the performance could be noticeably enhanced with a BHMF FE of 92.3% and HMF conversion of 98.5% at a potential of -0.15 V versus reversible hydrogen electrode(vs.RHE) in 0.1 M KOH solution.This work sheds light on the incomplete mechanistic puzzle for Cu-catalyzed electrochemical hydrogenation of HMF to BHMF,and provides a theoretical foundation for further precise design of highly efficient catalytic electrodes.展开更多
The facets effect on the catalytic properties of inorganic compounds and metal-organic frameworks(MOFs)has been widely demonstrated,but the intrinsic facets effect free of interference of capping agents has not been d...The facets effect on the catalytic properties of inorganic compounds and metal-organic frameworks(MOFs)has been widely demonstrated,but the intrinsic facets effect free of interference of capping agents has not been discussed.Here we give a proof-of-concept illustration on the intrinsic facets effect by employing the popularly investigated NH2-MIL-125(Ti)MOFs with{001},{111}and{100}facets controllably exposed as model photocatalysts,which were synthesized via a simple supersaturation strategy free of any capping agents.Compared to conventional synthetic routes with capping agents employed,the NH2-MIL-125(Ti)MOFs obtained in this work exhibit remarkably different physical and chemical properties such as surface wettability,charge separation as well as trend of facets effect on photocatalytic water splitting performance.The main reason has been unraveled to originate from unavoidable residue/influence of capping agents during the conventional facets-controlled synthetic routes leading to changed local surface structural environment as well as distinct charge separation property.Our results demonstrate the importance and feasibility of facets-controllable synthesis free of capping agents in getting insight into the intrinsic facets effect of MOFs-related materials.展开更多
Nanostructured ceria has attracted much attention in the field of redox catalysts due to the numerous active sites with excellent redox ability.Based on the acidic medium etching strategy,we constructed the strong bin...Nanostructured ceria has attracted much attention in the field of redox catalysts due to the numerous active sites with excellent redox ability.Based on the acidic medium etching strategy,we constructed the strong binding centers(hydroxyl sites and strong acid sites)on the surfaces of nanostructured ceria,which regulate the adsorption process of KA-Oil(the mixture of cyclohexanol and cyclohexanone)and to promote high KA-Oil selectivity in cyclohexane oxidation.The three CeO_(2)(nanocube,nanorod and nanopolyhedron)with different exposed crystal planes were treated by acid etching to change the surface sites and catalytic properties.The transition behavior of surface sites during etching was revealed,abundant strong binding centers were proved to be constructed successfully.And especially for the nanorod treated by acid(Acid@CeO_(2)-NR)with the strongest response for sulfuric acid etching,the strong adsorption of cyclohexanone by strong binding centers was confirmed based on the in-situ DRIFTs.The sulfuric acid etching strategy to enhance the selective oxidation of cyclohexane based on the construction of strong binding centers was proved to be feasible and effective,Acid@CeO_(2)-NR with strongest etching response achieved the dramatic promotion of KA-Oil selectivity from 64.1%to 92.3%.展开更多
Comprehensive fundamental understanding of CO hydrogenation reactions over Cu and ZnCu alloy surfaces is of great importance.Herein,we report a comparative DFT calculation study of elementary surface reaction network ...Comprehensive fundamental understanding of CO hydrogenation reactions over Cu and ZnCu alloy surfaces is of great importance.Herein,we report a comparative DFT calculation study of elementary surface reaction network of CO hydrogenation reactions on stepped Cu(211),Cu(611),ZnCu(211) and ZnCu(611)surfaces.On Zn Cu(211) and Zn Cu(611) surfaces,the energetic favorable reaction path of CO hydrogenation reaction follows CO^(*)→HCO^(*)→H_(2)CO^(*)→H_(3)CO^(*)→CH_(3)OH^(*)→CH_(3)OH with H_(3)CO^(*)hydrogenation as the rate-limiting step and proceeds more facilely on ZnCu(611) surface than on ZnCu(211) surface.On Cu(211) and Cu(611) surfaces,the energetic favorable reaction path of CO hydrogenation reaction follows CO^(*)→HCO^(*)→HCOH^(*)→H_(2)COH^(*)→H_(3)COH^(*)→CH_(3)^(*)→CH_(4)^(*)→CH_(4) with H_(2)COH^(*) hydrogenation as the rate-limiting step and proceeds more facilely on Cu(611) than on Cu(211).The key difference of CO hydrogenation reaction on Zn Cu alloy surface and Cu is that the resulting CH_(3)OH^(*) species desorbs to produce CH_(3)OH on ZnCu alloy but undergoes H^(*)-assisted decomposition to CH_(3)^(*) and eventually to CH_(4) on Cu surface.These results successfully unveil elementary surface reaction networks and structure sensitivity of Cu and Zn Cu alloy-catalyzed CO hydrogenation reactions.展开更多
Well-defined surface structures and uniformity are key factors in exploring structure–activity relationships in heterogeneous catalysts.A modified atomic layer deposition method and three well-defined CeO_(2) nanosha...Well-defined surface structures and uniformity are key factors in exploring structure–activity relationships in heterogeneous catalysts.A modified atomic layer deposition method and three well-defined CeO_(2) nanoshapes,octahedra with(111)surfaces,cubes exposing(100)facets,and rods with(100)and(110)surface facet terminations,were utilized to synthesize ultra-low loading Pt/CeO_(2) catalysts and allow investigations on the influence of ceria surface facet on isolated Pt species under reducing conditions.A mild reduction temperature(150℃)reduces the initial platinum ions present on the surfaces of the ceria support but preserves the isolated Pt atoms on all ceria surface facets.In contrast,a reduction temperature of 350°C,reveals very different interactions between the initial single Pt atoms and the various ceria surface facets,leading to dissimilar and nonuniform Pt ensembles on the three ceria shapes.To isolate facet dependent Pt–CeO_(2) interactions and avoid variations between Pt species,the Pt1/CeO_(2) catalysts after reduction at 150°C were subjected to CO oxidation conditions.The isolated Pt atoms on the CeO_(2) octahedra and cubes are less active in the CO oxidation reaction,compared with Pt on CeO_(2) rods.In the case of Pt on the CeO_(2) octahedra this is due to strongly bound CO blocking active sites together with a stable CeO_(2)(111)surface limiting the oxygen supply from the support.On the CeO_(2) cubes,some Pt is not available for reaction and CO is bound strongly on the available Pt species.In addition,the Pt catalysts supported on the CeO_(2) cubes are not stable with time on stream.The isolated Pt atoms on the CeO_(2) rods are considerably more active under these conditions and this is due to a weaker Pt–CO bond strength and more facile reverse oxygen spillover from the defect-rich(110)surfaces of the rods due to the lower energy of oxygen vacancy formation on this CeO_(2) surface.The Pt supported on the CeO_(2) rods is also remarkably stable with time on stream.This work demonstrates the importance of using ultra-low loadings of active metal and well-defined oxide supports to isolate interactions between single metal atoms and oxide supports and determine the effects of the oxide support surface facet on the active metal at the atomic level.展开更多
基金the National Natural Science Foundation of China(NSFC,Nos.51908218 and 21905092)the Youth Elite Sailing Program of Shanghai Institute of Technology(No.1021GK240006002-A07)+2 种基金Scientific Research Foundation of Shanghai Institute of Technology(No.10120K226156-A06-YJ2022-62)Shanghai Higher Education Institution Young Teacher Training Funding Program(No.ZZ202312031)the Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse(Nanjing University of Science and Technology)。
文摘The facet effect of metal-organic frameworks(MOF)on regulating the property of loaded co-catalysts is an important but unexplored issue in the field of photocatalysis.In this work,a series of MIL-125-NH_(2)polyhedrons(MIL=Materials Institute Lavoisier)with facet exposure of{001},{001}/{111}and{111}are synthesized and used to load Pd-based co-catalysts for photocatalytic oxygen reduction reaction(ORR)toward H_(2)O_(2)production.The different facets with distinct chemical environments(Ti-O clusters on{111}facets and carboxyl ligands on{001}facets)result in the selective loading of Pd0and PdO dominated cocatalysts on{001}and{111}facets,respectively.The{001}/{111}co-exposed MIL-125-NH_(2)thus enables the spatially separated loading of Pd0and Pd O dual cocatalysts respectively.Pd0efficiently traps the photoexcited electrons and PdO trends to capture the holes,collaboratively promoting the directional separation of photogenerated electron-hole pairs.As a result,the photocatalytic ORR activity is significantly enhanced with a H_(2)O_(2)production rate of 128.6 mmol L^(-1)g^(-1)h^(-1),superior than pristine and single cocatalyst modified MIL-125-NH_(2)samples.Our findings provide new insight into the design of high-performance photocatalysts.
基金supported by the National Natural Science Foundation of China (21808035, 21901040)the Natural Science Foundation of Fujian Province (2019J05058, 2021J05216, 2022J01922)+3 种基金the Fujian Provincial Department of Finance (GY-Z220231)the fund of the State Key Laboratory of Catalysis in DICP (N-22-08)the Fujian Fishery Disaster Reduction Center (GY-H-22146)College Student Innovation and Entrepreneurship Training Program (x202110388068)。
文摘The electrochemical hydrogenation of HMF to BHMF is an elegant alternative to the conventio nal thermocatalytic route for the production of high-value-added chemicals from biomass resources.In virtue of the wide potential window with promising Faradic efficiency(FE) towards BHMF,Cu-based electrode has been in the center of investigation.However,its structure-activity relationship remains ambiguous and its intrinsic catalytic activity is still unsatisfactory.In this work,we develop a two-step oxidation-reduction strategy to reconstruct the surface atom arrangement of the Cu foam(CF).By combination of multiple quasi-situ/in-situ techniques and density functional theory(DFT) calculation,the critical factor that governs the reaction is demonstrated to be facet effect of the metallic Cu crystal:Cu(110) facet accounts for the most favorable surface with enhanced chemisorption with reactants and selective production of BHMF,while Cu(100) facet might trigger the accumulation of the by-product 5,5'-bis(hydroxy methy)hydrofurion(BHH).With the optimized composition of the facets on the reconstructed Cu(OH)_(2)-ER/CF,the performance could be noticeably enhanced with a BHMF FE of 92.3% and HMF conversion of 98.5% at a potential of -0.15 V versus reversible hydrogen electrode(vs.RHE) in 0.1 M KOH solution.This work sheds light on the incomplete mechanistic puzzle for Cu-catalyzed electrochemical hydrogenation of HMF to BHMF,and provides a theoretical foundation for further precise design of highly efficient catalytic electrodes.
文摘The facets effect on the catalytic properties of inorganic compounds and metal-organic frameworks(MOFs)has been widely demonstrated,but the intrinsic facets effect free of interference of capping agents has not been discussed.Here we give a proof-of-concept illustration on the intrinsic facets effect by employing the popularly investigated NH2-MIL-125(Ti)MOFs with{001},{111}and{100}facets controllably exposed as model photocatalysts,which were synthesized via a simple supersaturation strategy free of any capping agents.Compared to conventional synthetic routes with capping agents employed,the NH2-MIL-125(Ti)MOFs obtained in this work exhibit remarkably different physical and chemical properties such as surface wettability,charge separation as well as trend of facets effect on photocatalytic water splitting performance.The main reason has been unraveled to originate from unavoidable residue/influence of capping agents during the conventional facets-controlled synthetic routes leading to changed local surface structural environment as well as distinct charge separation property.Our results demonstrate the importance and feasibility of facets-controllable synthesis free of capping agents in getting insight into the intrinsic facets effect of MOFs-related materials.
基金supported by National Natural Science Fund for Excellent Young Scholars(22222813)the National Natural Science Foundation of China(22078338)+2 种基金the National Key Research and Development Program of China(2023YFA1506803)the Postdoctoral Fellowship Program of CPSF(GZC20232700)the“Special Research Assistant Project”of the Chinese Academy of Sciences.
文摘Nanostructured ceria has attracted much attention in the field of redox catalysts due to the numerous active sites with excellent redox ability.Based on the acidic medium etching strategy,we constructed the strong binding centers(hydroxyl sites and strong acid sites)on the surfaces of nanostructured ceria,which regulate the adsorption process of KA-Oil(the mixture of cyclohexanol and cyclohexanone)and to promote high KA-Oil selectivity in cyclohexane oxidation.The three CeO_(2)(nanocube,nanorod and nanopolyhedron)with different exposed crystal planes were treated by acid etching to change the surface sites and catalytic properties.The transition behavior of surface sites during etching was revealed,abundant strong binding centers were proved to be constructed successfully.And especially for the nanorod treated by acid(Acid@CeO_(2)-NR)with the strongest response for sulfuric acid etching,the strong adsorption of cyclohexanone by strong binding centers was confirmed based on the in-situ DRIFTs.The sulfuric acid etching strategy to enhance the selective oxidation of cyclohexane based on the construction of strong binding centers was proved to be feasible and effective,Acid@CeO_(2)-NR with strongest etching response achieved the dramatic promotion of KA-Oil selectivity from 64.1%to 92.3%.
文摘采用湿化学法制备了立方体{100}、四面体{111}和菱形十二面体{110}磷酸银微晶,通过场发射扫描电镜(FE-SEM),X射线粉末衍射(XRD),固体紫外可见漫反射光谱(UV-Vis DRS),光电流,光致发光(PL)对催化剂的组分、结构、形貌及光电性质进行了系统表征。以罗丹明B(Rh B)为目标污染物,对不同形貌Ag_3PO_4微晶的可见光催化活性进行了探究。通过微热量技术结合过渡态理论和热化学循环原理对Ag_3PO_4的摩尔表面Gibbs自由能进行了测定,其数值分别为1.2972、0.9621、0.5414 k J?mol-1。采用自主设计的新型LED光-微热量系统获取了Ag_3PO_4原位光催化降解Rh B 2 h的热效应和稳定放热阶段的热焓变化率,并对其热谱曲线进行了合理的解析。结果表明,Ag_3PO_4的催化活性与原位光催化降解Rh B的热效应、热焓变化率以及摩尔表面Gibbs自由能皆呈正相关。此外,通过捕获剂实验和电子顺磁共振(ESR)确定了Ag_3PO_4光催化降解Rh B过程的主要活性基团。
基金financially supported by the National Natural Science Foundation of China (Nos. 91745202, 92145302)the Chinese Academy of Sciences, the Changjiang Scholars Program of Ministry of Education of China。
文摘Comprehensive fundamental understanding of CO hydrogenation reactions over Cu and ZnCu alloy surfaces is of great importance.Herein,we report a comparative DFT calculation study of elementary surface reaction network of CO hydrogenation reactions on stepped Cu(211),Cu(611),ZnCu(211) and ZnCu(611)surfaces.On Zn Cu(211) and Zn Cu(611) surfaces,the energetic favorable reaction path of CO hydrogenation reaction follows CO^(*)→HCO^(*)→H_(2)CO^(*)→H_(3)CO^(*)→CH_(3)OH^(*)→CH_(3)OH with H_(3)CO^(*)hydrogenation as the rate-limiting step and proceeds more facilely on ZnCu(611) surface than on ZnCu(211) surface.On Cu(211) and Cu(611) surfaces,the energetic favorable reaction path of CO hydrogenation reaction follows CO^(*)→HCO^(*)→HCOH^(*)→H_(2)COH^(*)→H_(3)COH^(*)→CH_(3)^(*)→CH_(4)^(*)→CH_(4) with H_(2)COH^(*) hydrogenation as the rate-limiting step and proceeds more facilely on Cu(611) than on Cu(211).The key difference of CO hydrogenation reaction on Zn Cu alloy surface and Cu is that the resulting CH_(3)OH^(*) species desorbs to produce CH_(3)OH on ZnCu alloy but undergoes H^(*)-assisted decomposition to CH_(3)^(*) and eventually to CH_(4) on Cu surface.These results successfully unveil elementary surface reaction networks and structure sensitivity of Cu and Zn Cu alloy-catalyzed CO hydrogenation reactions.
基金supported by the National Science Foundation(NSF)(CHE-1507230 and CBET-1933723)the National High Magnetic Field Laboratory,which is supported by the NSF Cooperative Agreement(DMR-1644779)and the State of Florida.Startup funding from the University of Florida is also gratefully acknowledged.
文摘Well-defined surface structures and uniformity are key factors in exploring structure–activity relationships in heterogeneous catalysts.A modified atomic layer deposition method and three well-defined CeO_(2) nanoshapes,octahedra with(111)surfaces,cubes exposing(100)facets,and rods with(100)and(110)surface facet terminations,were utilized to synthesize ultra-low loading Pt/CeO_(2) catalysts and allow investigations on the influence of ceria surface facet on isolated Pt species under reducing conditions.A mild reduction temperature(150℃)reduces the initial platinum ions present on the surfaces of the ceria support but preserves the isolated Pt atoms on all ceria surface facets.In contrast,a reduction temperature of 350°C,reveals very different interactions between the initial single Pt atoms and the various ceria surface facets,leading to dissimilar and nonuniform Pt ensembles on the three ceria shapes.To isolate facet dependent Pt–CeO_(2) interactions and avoid variations between Pt species,the Pt1/CeO_(2) catalysts after reduction at 150°C were subjected to CO oxidation conditions.The isolated Pt atoms on the CeO_(2) octahedra and cubes are less active in the CO oxidation reaction,compared with Pt on CeO_(2) rods.In the case of Pt on the CeO_(2) octahedra this is due to strongly bound CO blocking active sites together with a stable CeO_(2)(111)surface limiting the oxygen supply from the support.On the CeO_(2) cubes,some Pt is not available for reaction and CO is bound strongly on the available Pt species.In addition,the Pt catalysts supported on the CeO_(2) cubes are not stable with time on stream.The isolated Pt atoms on the CeO_(2) rods are considerably more active under these conditions and this is due to a weaker Pt–CO bond strength and more facile reverse oxygen spillover from the defect-rich(110)surfaces of the rods due to the lower energy of oxygen vacancy formation on this CeO_(2) surface.The Pt supported on the CeO_(2) rods is also remarkably stable with time on stream.This work demonstrates the importance of using ultra-low loadings of active metal and well-defined oxide supports to isolate interactions between single metal atoms and oxide supports and determine the effects of the oxide support surface facet on the active metal at the atomic level.
