A series CeO2（ZrO2）/TiO2 catalysts were modified with Er using a sol-gel method.The catalytic activity of the obtained catalysts in the selective catalytic reduction（SCR） of NO with NH3 was investigated to determi...A series CeO2（ZrO2）/TiO2 catalysts were modified with Er using a sol-gel method.The catalytic activity of the obtained catalysts in the selective catalytic reduction（SCR） of NO with NH3 was investigated to determine the appropriate Er dosage.The catalysts were characterized using X-ray diffraction,N2 adsorption,NH3 temperature-programmed desorption,H2 temperature-programmed reduction,photoluminescence spectroscopy,electron paramagnetic resonance spectroscopy,and X-ray photoelectron spectroscopy.The results showed that the optimum Er/Ce molar ratio was 0.10;this catalyst had excellent resistance to catalyst poisoning caused by vapor and sulfur and gave more than 90% NO conversion at 220–395 ℃ and a gas hourly space velocity of 71 400 h^-1.Er incorporation increased the Ti^3＋ concentrations,oxygen storage capacities,and oxygen vacancy concentrations of the catalysts,resulting in excellent catalytic performance.Er incorporation also decreased the acid strength and inhibited growth of TiO2 and CeO2 crystal particles,which increased the catalytic activity.The results show that high oxygen vacancy concentrations and oxygen storage capacities,large amounts of Ti^3＋,and low acid strengths give excellent SCR activity.展开更多
The effects of adding rare earth(RE) metals,such as Ce,Yb and Pr to Ni-S_2O_8^(2-)/ZrO_2-Al_2O_3(Ni-SZA) on the structure of catalysts as well as their isomerization performance were studied.The prepared catalysts wer...The effects of adding rare earth(RE) metals,such as Ce,Yb and Pr to Ni-S_2O_8^(2-)/ZrO_2-Al_2O_3(Ni-SZA) on the structure of catalysts as well as their isomerization performance were studied.The prepared catalysts were characterized by XRD,BET,FT-IR,Py-IR,and H_2-TPR,The results showed that the addition of RE metals can increase the strength and amounts of the acid sites,improve the redox properties of catalysts.The Yb-Ni-SZA catalyst showed the best redox properties,which could provide enough metallic sites.In addition,it provided the largest amounts of weak and moderately strong acid sites.Among RE metals modified Ni-SZA catalyst,Yb-Ni-SZA exhibited the highest isopentane yield of 61.7%at 160 °C.The optimum isomerization catalytic performance of the catalysts decreased in the order of Yb-Ni-SZA > Pr-Ni-SZA > Ni-SZA > Ce-Ni-SZA.展开更多
Hydrogen peroxide(H2O2)is a very useful chemical reagent,but the current industrial methods for its production suffer from serious energy consumption problems.Using high-activity and high-selectivity catalysts to elec...Hydrogen peroxide(H2O2)is a very useful chemical reagent,but the current industrial methods for its production suffer from serious energy consumption problems.Using high-activity and high-selectivity catalysts to electrocatalyze the oxygen reduction reaction(ORR)through a two-electron(2e^-)pathway is a very promising route to produce H2O2.In this work,we obtained partially oxidized multi-walled carbon nanotubes(MWCNTs)with controlled structure and composition by oxidation with concentrated sulfate and potassium permanganate at 40℃ for 1 h(O-CNTs-40-1).The outer layers of O-CNTs-40-1 are damaged with defects and oxygen-containing functional groups,while the inner layers are maintained intact.The optimized structure and composition of the partially oxidized MWCNTs ensure that O-CNTs-40-1 possesses both a sufficient number of catalytic sites and good conductivity.The results of rotating ring disk electrode measurements reveal that,among all oxidized MWCNTs,O-CNTs-40-1 shows the greatest improvement in hydrogen peroxide selectivity(from ~ 30% to ~ 50%)and electron transfer number(from ~ 3.4 to ~ 3.0)compared to those of the raw MWCNTs.The results of electrochemical impedance spectroscopy measurements indicate that both the charge-transfer and intrinsic resistances of O-CNTs-40-1 are lower than those of the raw MWCNTs and of the other oxidized MWCNTs.Finally,direct tests of the H2O2 production confirm the greatly improved catalytic activity of O-CNTs-40-1 relative to that of the raw MWCNTs.展开更多
Cerium oxide(ceria)plays an important and fascinating role in heterogeneous catalysis as illustrated by its versatile use as a catalyst,a catalyst support,or a promotor in various oxidation and reduction reactions.Cen...Cerium oxide(ceria)plays an important and fascinating role in heterogeneous catalysis as illustrated by its versatile use as a catalyst,a catalyst support,or a promotor in various oxidation and reduction reactions.Central to these reactions is the rich defect chemistry,facile redox capability,and unusual acid-base properties of ceria.Understanding the unique redox and acid-base properties of ceria is essential to build the structure-catalysis relationship so that improved catalytic functions can be achieved for ceria-based materials.Among the characterization toolbox,spectroscopic approach indisputably stands out for its unparalleled power in offering chemical insights into the surface properties of ceria at atomic and molecular level.In this review,we summarize advances in revealing the redox and acid-base properties of ceria via a variety of spectroscopic methods including optical,X-ray,neutron,electronic and nuclear spectroscopy.Both direct spectroscopy characterization and its coupling with probe molecules are analyzed to illustrate how the nature,strength and density of different surface sites are influenced by the pretreatment,the morphology and size of ceria nanoparticles.Further directions in taking advantage of in situ/operando spectroscopy for better understanding the catalysis of ceria-based materials are proposed in the summary and outlook section.展开更多
Ultrasmall gold nanoclusters consisting of 2-4 Au atoms were synthesized and their per- formance in electrocatalytic oxygen reduction reactions （ORR） was examined. These clus- ters were synthesized by exposing AuPPh...Ultrasmall gold nanoclusters consisting of 2-4 Au atoms were synthesized and their per- formance in electrocatalytic oxygen reduction reactions （ORR） was examined. These clus- ters were synthesized by exposing AuPPh3Cl to the aqueous ammonia medium for one week. Electrospray ionization mass spectrometry （ESI-MS）, X-ray absorption fihe struc- ture （XAFS）, and X-ray photoelectron spectroscopy （XPS） analyses indicate that the as- synthesized gold clusters （abbreviated as Aux） consist of 2-4 Au atoms coordinated by the triphenylphosphine, hydroxyl, and adsorbed oxygen ligands. A glassy carbon disk electrode loaded with the Aux clusters （Aux/GC） was characterized by the cyclic and linear-sweep voltammetry for ORR. The cyclic voltammogram vs. RHE shows the onset potential of 0.87 V, and the kinetic parameters of JK at 0.47 V and the electron-transfer mmlber per oxygen molecule were calculated to be 14.28 mA/cm2 and 3.96 via the Koutecky-Levich equations, respectively.展开更多
Triuranium octoxide-reduced graphene oxide （U3O8/rGO） hybrids have been prepared by a two-step solution-phase method. The presence of GO is essential in order to obtain pure phase U3O8. The U3O8/rGO hybrids exhibite...Triuranium octoxide-reduced graphene oxide （U3O8/rGO） hybrids have been prepared by a two-step solution-phase method. The presence of GO is essential in order to obtain pure phase U3O8. The U3O8/rGO hybrids exhibited excellent electrocatalytic activity for the oxygen reduction reaction. The electron transfer number was calculated to be -3.9 at -0.7 V （vs. Ag/AgCl） from the slope of the Koutecky-Levich plots. The U3O8/rGO hybrids were more stable than commercial Pt/C catalysts. Furthermore, when methanol was present, the U3O8/rGO hybrids still retained high activity. In addition, the UBO8/rGO hybrids can also catalyze the reduction of hydrogen peroxide.展开更多
Pt3Ni nanoparticles have been obtained by shape-controlled synthesis and employed as oxygen reduction electrocatalysts for proton exchange membrane fuel cells （PEMFC）. The effects of varying the synthesis parameters...Pt3Ni nanoparticles have been obtained by shape-controlled synthesis and employed as oxygen reduction electrocatalysts for proton exchange membrane fuel cells （PEMFC）. The effects of varying the synthesis parameters such as the types of the capping agent and the reducing agent, and the reaction time have been systematically studied. The as-prepared PtBNi nanoparticles were subjected to a butylamine-based surface treatment in order to prepare carbon-supported electrocatalysts. The Pt3Ni electrocatalysts show an area- specific activity of 0.76 mA/cm2（pt） at 0.9 V in an alkaline electrolyte, which is 4.5 times that of a commercial Pt/C catalyst （0.17 mA/cm2 （Pt））. The mass activity reached 0.30 A/mg（Pt） at 0.9 V, which is about twice that of the commercial Pt/C catalyst. Our results also show that the area-specific activities of these carbon-supported Pt3Ni electrocatalysts depend strongly on the （111） surface fraction, which is consistent with the results of a study based on Pt3Ni extended single-crystal surfaces.展开更多
MXenes, a new family of multifunctional two dimensional(2D) solid crystals integrating high electroconductivity and rich surface chemistries, are promising candidates for electrolysis, which, however, have rarely been...MXenes, a new family of multifunctional two dimensional(2D) solid crystals integrating high electroconductivity and rich surface chemistries, are promising candidates for electrolysis, which, however, have rarely been reported. Herein, free-standing ultrathin 2D MXene nanosheets were successfully fabricated from bulky and rigid MAX phase ceramics by liquid exfoliation with HF etching(delamination) and TPAOH intercalation(disintegration).The high oxygen reduction reaction(ORR) performance has been obtained, due to the extremely small thickness of the asfabricated Ti3C2 around 0.5–2.0 nm, equivalent to the dimensions of single-layer or double-layer Ti3C2 nanosheets in thickness. The ORR performance of the obtained Ti3C2 MXene-based catalyst exhibits desirable activity and stability in alkaline media. This study demonstrates the potential of earth-abundant 2D MXenes for constructing high-performance and cost-effective electrocatalysts.展开更多
Sn-based electrocatalysts have been gaining increasing attention due to their potential contribution in the conversion of CO2 into HCOOH driven by sustainable energy sources;however,their actual capability to catalyze...Sn-based electrocatalysts have been gaining increasing attention due to their potential contribution in the conversion of CO2 into HCOOH driven by sustainable energy sources;however,their actual capability to catalyze CO2 reduction reaction(CO2RR)still cannot meet the requirements of commercial-scale applications.Therefore developing Snbased catalyst is of vital importance.Herein,the sheet-like heterophase Sn O2/Sn3O4 with a high density of phase interfaces has been first engineered by a facile hydrothermal process,with Sn3O4 as the dominant phase.The evidences from experiments and theoretical simulation indicate that the charge redistribution and built-in electric field at heterophase interfaces boost CO2 adsorption and HCOO*formation,accelerate the charge transfer between the catalysts and reactants,and ultimately greatly elevate the intrinsic activity of the heterophase Sn O2/Sn3O4 towards CO2 RR.Meanwhile,the in-situ generated porous structure and metal Sn during CO2 RR improve the mass transmission within the interlayer volume and the conductivity of Sn O2/Sn3O4.The heterophase Sn O2/Sn3O4 displays high activity and selectivity for CO2 RR,achieving an improvement in CO2 reduction current density,88.3%Faradaic efficiency of HCOOH conversion at-0.9 VRHE,along with a long-term tolerance in CO2 RR.This study demonstrates that heterophase interface engineering is an efficient strategy to regulate advanced catalysts for different applications.展开更多
A facile synthetic strategy was developed for insitu preparation of two-dimensional (2D)highly crystalline tungsten nitride (WN)nanosheets with controllable morphology as oxygen reduction reaction (ORR)catalysts.The d...A facile synthetic strategy was developed for insitu preparation of two-dimensional (2D)highly crystalline tungsten nitride (WN)nanosheets with controllable morphology as oxygen reduction reaction (ORR)catalysts.The dependence of the crystal structure and morphology of WN on K2SO4content,pH,and pyrolysis temperature was thoroughly examined.The electrocatalytic performance of WN toward ORR in an alkaline electrolyte indicated that K+plays an important role in the control of size and shape in the hydrothermal and nitridation process,thereby promoting the formation of plate-like WO3and 2D WN nanosheets.The WN nanosheets,with largely exposed edge sites,provide abundant catalytic active sites and allow fast charge transfer.Furthermore,they exhibit high stability for ORR and methanol tolerance.展开更多
An efficient photocatalytic CO_(2) reduction has been reported in ZIF-67-derived-Co nanoparticles(NPs)encapsulated in nitrogen-doped carbon layers(N-C/Co).This work demonstrates that the pyrolysis temperature is cruci...An efficient photocatalytic CO_(2) reduction has been reported in ZIF-67-derived-Co nanoparticles(NPs)encapsulated in nitrogen-doped carbon layers(N-C/Co).This work demonstrates that the pyrolysis temperature is crucial in tuning the grain size and components of metallic Co^(0) of N-C/Co composite catalysts,which optimizes their photocatalytic activities.Syntheses were conducted at 600,700,and 800℃ giving the N-C/Co-600,N-C/Co-700,and N-C/Co-800 samples,respectively.N-C layers can well wrap the Co NPs obtained at a low pyrolysis temperature(600℃)owing to their smaller grains than those of other samples.A high metallic Co^(0) content in the N-C/Co-600 sample can be attributed to the effective inhibition of surface oxidation.By contrast,the surface CoOx oxides in the N-C/Co-700 and N-C/Co-800 samples cover inside Co cores,inhibiting charge separation and transfer.As a result,the N-C/Co-600 sample yields the best photocatalytic activity.The carbon monoxide and hydrogen generation rates are as high as 1.62×10^(4) and 2.01×10^(4)μmol g^(−1)h^(−1),respectively.Additionally,the Co NPs make composite catalysts magnetic,enabling rapid and facile recovery of catalysts with the assistance of an external magnetic field.This work is expected to provide an instructive guideline for designing metal-organic framework-derived carbon/metal composite catalysts.展开更多
Ordered mesoporous Cu-Mg-A1 composite oxides were synthesized via the one-pot evaporation-in- duced self-assembly strategy. Using this method, copper was first homogeneously incorporated into the ordered mesoporous sp...Ordered mesoporous Cu-Mg-A1 composite oxides were synthesized via the one-pot evaporation-in- duced self-assembly strategy. Using this method, copper was first homogeneously incorporated into the ordered mesoporous spinel matrix. After H2 reduction treatment, according to X-ray diffraction （XRD） and transmission electron microscopy （TEM） results, copper existed as metallic nanoparticles with the size of 6-10 nm that well decorated the parent mesoporous skeleton. The metallic nanoparticles were then re-oxidized to copper oxide when exposed to air or during CO oxidation reaction at low temperatures. Thus, copper migrated from bulk spinel phase to the surface after the reduction-oxidation treat- ment. Moreover, the copper on the surface was re-incor- porated into the bulk spinel phase by further thermal treatment at much higher temperature in the presence of air. The correlation between the state of copper in the mesoporous composite oxides and the catalytic perfor- mance toward CO oxidation was studied. It was found that copper existed as oxide nanoparticles on the surface of mesoporous Mg-Al skeleton is much more active than that existed as lattice Cu ions in spinel phase.展开更多
基金supported by the National Natural Science Foundation of China(51272105)Jiangsu Provincial Science and Technology Supporting Program(BE2013718)+1 种基金Research Subject of Environmental Protection Department of Jiangsu Province of China(2013006)Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)~~
文摘A series CeO2（ZrO2）/TiO2 catalysts were modified with Er using a sol-gel method.The catalytic activity of the obtained catalysts in the selective catalytic reduction（SCR） of NO with NH3 was investigated to determine the appropriate Er dosage.The catalysts were characterized using X-ray diffraction,N2 adsorption,NH3 temperature-programmed desorption,H2 temperature-programmed reduction,photoluminescence spectroscopy,electron paramagnetic resonance spectroscopy,and X-ray photoelectron spectroscopy.The results showed that the optimum Er/Ce molar ratio was 0.10;this catalyst had excellent resistance to catalyst poisoning caused by vapor and sulfur and gave more than 90% NO conversion at 220–395 ℃ and a gas hourly space velocity of 71 400 h^-1.Er incorporation increased the Ti^3＋ concentrations,oxygen storage capacities,and oxygen vacancy concentrations of the catalysts,resulting in excellent catalytic performance.Er incorporation also decreased the acid strength and inhibited growth of TiO2 and CeO2 crystal particles,which increased the catalytic activity.The results show that high oxygen vacancy concentrations and oxygen storage capacities,large amounts of Ti^3＋,and low acid strengths give excellent SCR activity.
基金Supported by the Technology Risk Innovation Foundation of China National Petroleum Corporation(07-06D-01-04-03-02)
文摘The effects of adding rare earth(RE) metals,such as Ce,Yb and Pr to Ni-S_2O_8^(2-)/ZrO_2-Al_2O_3(Ni-SZA) on the structure of catalysts as well as their isomerization performance were studied.The prepared catalysts were characterized by XRD,BET,FT-IR,Py-IR,and H_2-TPR,The results showed that the addition of RE metals can increase the strength and amounts of the acid sites,improve the redox properties of catalysts.The Yb-Ni-SZA catalyst showed the best redox properties,which could provide enough metallic sites.In addition,it provided the largest amounts of weak and moderately strong acid sites.Among RE metals modified Ni-SZA catalyst,Yb-Ni-SZA exhibited the highest isopentane yield of 61.7%at 160 °C.The optimum isomerization catalytic performance of the catalysts decreased in the order of Yb-Ni-SZA > Pr-Ni-SZA > Ni-SZA > Ce-Ni-SZA.
基金supported by the National Natural Science Foundation of China(21576299,21576300)Guangzhou Science and Technology Project(201607010104,201707010079)+3 种基金Science and Technology Planning Project of Guangdong Province(2017A050501009)the National Key Research and Development Program of China(2016YFB0101204)Tip-top Scientific and Technical Innovative Youth Talents of Guangdong Special Support Program(2016TQ03N322)the fundamental Research Funds for Central Universities(17lgzd14)~~
文摘Hydrogen peroxide(H2O2)is a very useful chemical reagent,but the current industrial methods for its production suffer from serious energy consumption problems.Using high-activity and high-selectivity catalysts to electrocatalyze the oxygen reduction reaction(ORR)through a two-electron(2e^-)pathway is a very promising route to produce H2O2.In this work,we obtained partially oxidized multi-walled carbon nanotubes(MWCNTs)with controlled structure and composition by oxidation with concentrated sulfate and potassium permanganate at 40℃ for 1 h(O-CNTs-40-1).The outer layers of O-CNTs-40-1 are damaged with defects and oxygen-containing functional groups,while the inner layers are maintained intact.The optimized structure and composition of the partially oxidized MWCNTs ensure that O-CNTs-40-1 possesses both a sufficient number of catalytic sites and good conductivity.The results of rotating ring disk electrode measurements reveal that,among all oxidized MWCNTs,O-CNTs-40-1 shows the greatest improvement in hydrogen peroxide selectivity(from ~ 30% to ~ 50%)and electron transfer number(from ~ 3.4 to ~ 3.0)compared to those of the raw MWCNTs.The results of electrochemical impedance spectroscopy measurements indicate that both the charge-transfer and intrinsic resistances of O-CNTs-40-1 are lower than those of the raw MWCNTs and of the other oxidized MWCNTs.Finally,direct tests of the H2O2 production confirm the greatly improved catalytic activity of O-CNTs-40-1 relative to that of the raw MWCNTs.
文摘Cerium oxide(ceria)plays an important and fascinating role in heterogeneous catalysis as illustrated by its versatile use as a catalyst,a catalyst support,or a promotor in various oxidation and reduction reactions.Central to these reactions is the rich defect chemistry,facile redox capability,and unusual acid-base properties of ceria.Understanding the unique redox and acid-base properties of ceria is essential to build the structure-catalysis relationship so that improved catalytic functions can be achieved for ceria-based materials.Among the characterization toolbox,spectroscopic approach indisputably stands out for its unparalleled power in offering chemical insights into the surface properties of ceria at atomic and molecular level.In this review,we summarize advances in revealing the redox and acid-base properties of ceria via a variety of spectroscopic methods including optical,X-ray,neutron,electronic and nuclear spectroscopy.Both direct spectroscopy characterization and its coupling with probe molecules are analyzed to illustrate how the nature,strength and density of different surface sites are influenced by the pretreatment,the morphology and size of ceria nanoparticles.Further directions in taking advantage of in situ/operando spectroscopy for better understanding the catalysis of ceria-based materials are proposed in the summary and outlook section.
基金supported by the National Natural Science Foundation of China(No.11475176,No.U1632263,and No.21533007)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.11621063)
文摘Ultrasmall gold nanoclusters consisting of 2-4 Au atoms were synthesized and their per- formance in electrocatalytic oxygen reduction reactions （ORR） was examined. These clus- ters were synthesized by exposing AuPPh3Cl to the aqueous ammonia medium for one week. Electrospray ionization mass spectrometry （ESI-MS）, X-ray absorption fihe struc- ture （XAFS）, and X-ray photoelectron spectroscopy （XPS） analyses indicate that the as- synthesized gold clusters （abbreviated as Aux） consist of 2-4 Au atoms coordinated by the triphenylphosphine, hydroxyl, and adsorbed oxygen ligands. A glassy carbon disk electrode loaded with the Aux clusters （Aux/GC） was characterized by the cyclic and linear-sweep voltammetry for ORR. The cyclic voltammogram vs. RHE shows the onset potential of 0.87 V, and the kinetic parameters of JK at 0.47 V and the electron-transfer mmlber per oxygen molecule were calculated to be 14.28 mA/cm2 and 3.96 via the Koutecky-Levich equations, respectively.
文摘Triuranium octoxide-reduced graphene oxide （U3O8/rGO） hybrids have been prepared by a two-step solution-phase method. The presence of GO is essential in order to obtain pure phase U3O8. The U3O8/rGO hybrids exhibited excellent electrocatalytic activity for the oxygen reduction reaction. The electron transfer number was calculated to be -3.9 at -0.7 V （vs. Ag/AgCl） from the slope of the Koutecky-Levich plots. The U3O8/rGO hybrids were more stable than commercial Pt/C catalysts. Furthermore, when methanol was present, the U3O8/rGO hybrids still retained high activity. In addition, the UBO8/rGO hybrids can also catalyze the reduction of hydrogen peroxide.
文摘Pt3Ni nanoparticles have been obtained by shape-controlled synthesis and employed as oxygen reduction electrocatalysts for proton exchange membrane fuel cells （PEMFC）. The effects of varying the synthesis parameters such as the types of the capping agent and the reducing agent, and the reaction time have been systematically studied. The as-prepared PtBNi nanoparticles were subjected to a butylamine-based surface treatment in order to prepare carbon-supported electrocatalysts. The Pt3Ni electrocatalysts show an area- specific activity of 0.76 mA/cm2（pt） at 0.9 V in an alkaline electrolyte, which is 4.5 times that of a commercial Pt/C catalyst （0.17 mA/cm2 （Pt））. The mass activity reached 0.30 A/mg（Pt） at 0.9 V, which is about twice that of the commercial Pt/C catalyst. Our results also show that the area-specific activities of these carbon-supported Pt3Ni electrocatalysts depend strongly on the （111） surface fraction, which is consistent with the results of a study based on Pt3Ni extended single-crystal surfaces.
基金financially supported by the National Key R&D Program of China (2016YFA0203700)the National Natural Science Foundation of China (51702099, 51672303 and 51722211)+5 种基金the Program of Shanghai Academic Research Leader (18XD1404300)Young Elite Scientist Sponsorship Program by CAST (2015QNRC001)Youth Innovation Promotion Association of the Chinese Academy of Sciences (2013169)Shanghai Sailing Program (17YF1403800)China Postdoctoral Science Foundation funded project (2017M611500)the Opening Project of State Key Laboratory of High Performance Ceramics and Superfine Microstructure (SKL201702SIC)
文摘MXenes, a new family of multifunctional two dimensional(2D) solid crystals integrating high electroconductivity and rich surface chemistries, are promising candidates for electrolysis, which, however, have rarely been reported. Herein, free-standing ultrathin 2D MXene nanosheets were successfully fabricated from bulky and rigid MAX phase ceramics by liquid exfoliation with HF etching(delamination) and TPAOH intercalation(disintegration).The high oxygen reduction reaction(ORR) performance has been obtained, due to the extremely small thickness of the asfabricated Ti3C2 around 0.5–2.0 nm, equivalent to the dimensions of single-layer or double-layer Ti3C2 nanosheets in thickness. The ORR performance of the obtained Ti3C2 MXene-based catalyst exhibits desirable activity and stability in alkaline media. This study demonstrates the potential of earth-abundant 2D MXenes for constructing high-performance and cost-effective electrocatalysts.
基金the National Natural Science Foundation of China(21573062,21631004 and 21901065)the Natural Science Foundation of Heilongjiang Province(B2018008)+1 种基金the Youth Science and Technology Innovation Team Project of Heilongjiang Province(2018-KYYWF-1593)the University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province(UNPYSCT-2018009)。
文摘Sn-based electrocatalysts have been gaining increasing attention due to their potential contribution in the conversion of CO2 into HCOOH driven by sustainable energy sources;however,their actual capability to catalyze CO2 reduction reaction(CO2RR)still cannot meet the requirements of commercial-scale applications.Therefore developing Snbased catalyst is of vital importance.Herein,the sheet-like heterophase Sn O2/Sn3O4 with a high density of phase interfaces has been first engineered by a facile hydrothermal process,with Sn3O4 as the dominant phase.The evidences from experiments and theoretical simulation indicate that the charge redistribution and built-in electric field at heterophase interfaces boost CO2 adsorption and HCOO*formation,accelerate the charge transfer between the catalysts and reactants,and ultimately greatly elevate the intrinsic activity of the heterophase Sn O2/Sn3O4 towards CO2 RR.Meanwhile,the in-situ generated porous structure and metal Sn during CO2 RR improve the mass transmission within the interlayer volume and the conductivity of Sn O2/Sn3O4.The heterophase Sn O2/Sn3O4 displays high activity and selectivity for CO2 RR,achieving an improvement in CO2 reduction current density,88.3%Faradaic efficiency of HCOOH conversion at-0.9 VRHE,along with a long-term tolerance in CO2 RR.This study demonstrates that heterophase interface engineering is an efficient strategy to regulate advanced catalysts for different applications.
基金supported by the National Natural Science Foundation of China(21306119)the Key Research and Development Projects in Sichuan Province(2017GZ0397,2017CC0017)the Science and Technology Project of Chengdu(2015-HM01-00531-SF)
文摘A facile synthetic strategy was developed for insitu preparation of two-dimensional (2D)highly crystalline tungsten nitride (WN)nanosheets with controllable morphology as oxygen reduction reaction (ORR)catalysts.The dependence of the crystal structure and morphology of WN on K2SO4content,pH,and pyrolysis temperature was thoroughly examined.The electrocatalytic performance of WN toward ORR in an alkaline electrolyte indicated that K+plays an important role in the control of size and shape in the hydrothermal and nitridation process,thereby promoting the formation of plate-like WO3and 2D WN nanosheets.The WN nanosheets,with largely exposed edge sites,provide abundant catalytic active sites and allow fast charge transfer.Furthermore,they exhibit high stability for ORR and methanol tolerance.
基金financially supported by the National Key Research and Development Program of China(2020YFA0710303)the National Natural Science Foundation of China(51972061,U1905215 and 52072076)。
文摘An efficient photocatalytic CO_(2) reduction has been reported in ZIF-67-derived-Co nanoparticles(NPs)encapsulated in nitrogen-doped carbon layers(N-C/Co).This work demonstrates that the pyrolysis temperature is crucial in tuning the grain size and components of metallic Co^(0) of N-C/Co composite catalysts,which optimizes their photocatalytic activities.Syntheses were conducted at 600,700,and 800℃ giving the N-C/Co-600,N-C/Co-700,and N-C/Co-800 samples,respectively.N-C layers can well wrap the Co NPs obtained at a low pyrolysis temperature(600℃)owing to their smaller grains than those of other samples.A high metallic Co^(0) content in the N-C/Co-600 sample can be attributed to the effective inhibition of surface oxidation.By contrast,the surface CoOx oxides in the N-C/Co-700 and N-C/Co-800 samples cover inside Co cores,inhibiting charge separation and transfer.As a result,the N-C/Co-600 sample yields the best photocatalytic activity.The carbon monoxide and hydrogen generation rates are as high as 1.62×10^(4) and 2.01×10^(4)μmol g^(−1)h^(−1),respectively.Additionally,the Co NPs make composite catalysts magnetic,enabling rapid and facile recovery of catalysts with the assistance of an external magnetic field.This work is expected to provide an instructive guideline for designing metal-organic framework-derived carbon/metal composite catalysts.
基金This work was supported by the Recruitment Program of Global Youth Experts of China, the National Natural Science Foundation of China （21403267, 21450110410）, and Shandong Postdoctoral Innovation Program （201303065）.
文摘Ordered mesoporous Cu-Mg-A1 composite oxides were synthesized via the one-pot evaporation-in- duced self-assembly strategy. Using this method, copper was first homogeneously incorporated into the ordered mesoporous spinel matrix. After H2 reduction treatment, according to X-ray diffraction （XRD） and transmission electron microscopy （TEM） results, copper existed as metallic nanoparticles with the size of 6-10 nm that well decorated the parent mesoporous skeleton. The metallic nanoparticles were then re-oxidized to copper oxide when exposed to air or during CO oxidation reaction at low temperatures. Thus, copper migrated from bulk spinel phase to the surface after the reduction-oxidation treat- ment. Moreover, the copper on the surface was re-incor- porated into the bulk spinel phase by further thermal treatment at much higher temperature in the presence of air. The correlation between the state of copper in the mesoporous composite oxides and the catalytic perfor- mance toward CO oxidation was studied. It was found that copper existed as oxide nanoparticles on the surface of mesoporous Mg-Al skeleton is much more active than that existed as lattice Cu ions in spinel phase.
