Cu nanoparticles supported on a variety of oxide supports, including SiO2, TiO2, ZrO2, Al2O3, MgO and ZnO, were investigated for the hydrogenolysis of biomass‐derived furfuryl alcohol to1,2‐pentanediol and 1,5‐pent...Cu nanoparticles supported on a variety of oxide supports, including SiO2, TiO2, ZrO2, Al2O3, MgO and ZnO, were investigated for the hydrogenolysis of biomass‐derived furfuryl alcohol to1,2‐pentanediol and 1,5‐pentanediol. A Cu‐Al2O3 catalyst with 10 wt% Cu loading prepared by a co‐precipitation method exhibited the best performance in terms of producing pentanediols compared with the other materials. This catalyst generated an 85.8% conversion and a 70.3% combined selectivity for the target pentanediols at 413 K and 8 MPa H2 over an 8‐h reaction. The catalyst could also be recycled over repeated reaction trials without any significant decrease in productivity. Characterizations with X‐ray diffraction, NH3/CO2‐temperature programmed desorption, N2 adsorption,transmission electron microscopy and N2 O chemisorption demonstrated that intimate and effective interactions between Cu particles and the acidic Al2O3 support in this material greatly enhanced its activity and selectivity. The promotion of the hydrogenolysis reaction was found to be especially sensitive to the Cu particle size, and the catalyst with Cu particles 1.9 to 2.4 nm in size showed the highest turnover frequency during the synthesis of pentanediols.展开更多
Using Cu-BTC prepared by hydrothermal method as precursor, carbon-based catalysts were obtained as model materials for low-temperature DeNO_x. These catalysts were characterized by X-ray diffractometry（XRD）, Raman s...Using Cu-BTC prepared by hydrothermal method as precursor, carbon-based catalysts were obtained as model materials for low-temperature DeNO_x. These catalysts were characterized by X-ray diffractometry（XRD）, Raman spectroscopy, scanning electron microscopy（SEM） and energy dispersive X-ray spectrometry（EDS）. The results showed that all carbon-based catalysts held the octahedron shape of Cu-BTC in most parts, and they mainly consisted of face-centered cubic copper. CuO_x/C exhibited excellent catalytic activity, and such catalytic activity was further improved with the introduction of Ag. The catalyst with a Cu to Ag mole ratio of 6：1 and an activated temperature of 600 °C showed the best catalytic performance, and its catalytic denitration rate reached 100% at a temperature as low as 235 °C. During the catalytic reaction process, Cu~＋ mainly played a catalytic role.展开更多
Cu-based catalysts are commonly used in industry for methanol synthesis.In this study,supported catalysts of 5 wt%Cu/Al_(2)O_(3)and 5 wt%Cu/ZnO were prepared,and their surface characteristics during H_(2) reduction an...Cu-based catalysts are commonly used in industry for methanol synthesis.In this study,supported catalysts of 5 wt%Cu/Al_(2)O_(3)and 5 wt%Cu/ZnO were prepared,and their surface characteristics during H_(2) reduction and CO_(2)hydrogenation were investigated using in situ Fourier transform infrared spectroscopy(FTIR),ex situ X-ray photoelectron spectroscopy,and high sensitivity low energy ion scattering spectroscopy.During the H2 reduction and CO_(2)hydrogenation processes,it was found that Al_(2)O_(3)can stabilize Cu^(+).In situ FTIR spectra indicated that the 5 wt%Cu/Al_(2)O_(3)can adsorb large amounts of bicarbonate and carbonate species,which then convert into formate during CO_(2)hydrogenation.For the 5 wt%Cu/ZnO,it was found that Cu nanoparticles were gradually covered by a highly defective ZnOx overlayer during H2 reduction,which can effectively dissociate H2.During CO_(2)hydrogenation,the adsorbed bicarbonate or carbonate species can convert into formate and then into a methoxy species.Using these surface sensitive methods,a more in-depth understanding of the synergistic effect among the Cu,Al_(2)O_(3),and ZnO components of Cu-based catalysts was achieved.展开更多
Electroreduction of greenhouse gas CO_(2) into value-added fuels and chemicals provides a promising pathway to address the issues of energy crisis and environmental change.However,the regulations of the selectivity to...Electroreduction of greenhouse gas CO_(2) into value-added fuels and chemicals provides a promising pathway to address the issues of energy crisis and environmental change.However,the regulations of the selectivity towards C2 product and the competing hydrogen evolution reaction(HER)are major challenges for CO_(2) reduction reaction(CO_(2)RR).Here,we develop an interface-enhanced strategy by depositing a thin layer of nitrogen-doped graphene(N-G)on a Cu foam surface(Cu-N-G)to selectively promote the ethanol pathway in CO_(2)RR.Compared to the undetectable ethanol selectivity of pure Cu and Cu@graphene(Cu-G),Cu-N-G has boosted the ethanol selectivity to 33.1%in total Faradic efficiency(FE)at−0.8 V vs.reversible hydrogen electrode(RHE).The experimental and density functional theory(DFT)results verify that the interconnected graphene coating can not only serve as the fast charge transport channel but also provide confined nanospace for mass transfer.The N doping can not only trigger the intrinsic interaction between N in N-G and CO_(2) molecule for enriching the local concentration of reactants but also promote the average valence state of Cu for C–C coupling pathways.The confinement effect at the interface of Cu-N-G can not only provide high adsorbed hydrogen(Had)coverage but also stabilize the key*HCCHOH intermediate towards ethanol pathway.The provided interface-enhanced strategy herein is expected to inspire the design of Cubased CO_(2)RR electrocatalysts towards multi-carbon products.展开更多
Electrocatalytic CO_(2) reduction reaction(ECO_(2)RR)converts CO_(2) to high-value chemical products and promotes the carbon cycle.Sulfur(S)-modified copper(Cu)and bismuth(Bi)-based catalysts have been recognized as p...Electrocatalytic CO_(2) reduction reaction(ECO_(2)RR)converts CO_(2) to high-value chemical products and promotes the carbon cycle.Sulfur(S)-modified copper(Cu)and bismuth(Bi)-based catalysts have been recognized as promising catalysts for ECO_(2)RR.Both of them are highly active for selective formate generation,however,their poor stability and severe competing hydrogen evolution reaction(HER)remain challenging.Herein,S-doped Cu coated with Bi(Bi/Cu-S)is developed to improve ECO_(2)RR selectivity to formate.Bi/Cu-S/brass mesh(BM)electrode material for ECO_(2)RR was prepared by electrodepositing Bi on the surface of Cu-S/BM nanowires obtained from CuS/BM after the electroreduction.The Faradaic efficiency(FE)of the formate reaches the maximum of 94.3%at-0.9 V vs.reversible hydrogen electrode(RHE)with a partial current density as high as-50.7 mA·cm^(-2) and a yield of 30.7 mmol·h^(-1)·cm^(-2) under 0.5 M KHCO_(3) electrolyte.Meanwhile,the FE of formate is higher than 90%in the voltage range of-0.8 to-1.0 V vs.RHE.It also shows good stability at-0.9 V vs.RHE with the FE of formate remaining above 93%after a 10 h reaction.Density functional theory(DFT)calculations demonstrate that the Bi/Cu-S structure promotes the adsorption of CO_(2) and effectively inhibits HER by enhancing the adsorption of^(*)H to a great extent,improving the selective conversion of CO_(2) to formate.This work deepens the understanding of the mechanism of Cu-Bi-based catalysts and S-modified Cu-based catalysts in selective ECO_(2)RR to formate,and also provides a new strategy for catalyst design.展开更多
Electrochemical NO reduction reaction(NORR)to generate NH_(3)emerges as a fascinating approach to achieve both NO pollution mitigation and sustainable NH_(3)synthesis.Herein,we demonstrate that single-atomic Cu anchor...Electrochemical NO reduction reaction(NORR)to generate NH_(3)emerges as a fascinating approach to achieve both NO pollution mitigation and sustainable NH_(3)synthesis.Herein,we demonstrate that single-atomic Cu anchored on MoS_(2)(Cu_(1)/MoS_(2))comprising Cu_(1)-S_(3)motifs can serve as a highly efficient NORR catalyst.Cu1/MoS_(2)exhibits an NH_(3)yield rate of 337.5μmol·h^(−1)·cm^(−2)with a Faradaic efficiency of 90.6%at−0.6 V vs.reversible hydrogen electrode(RHE).Combined experiments and theoretical calculations reveal that Cu1-S3 motifs enable the effective activation and hydrogenation of NO through a mixed pathway and simultaneously retard proton coverage,contributing to the high activity and selectivity of Cu1/MoS_(2)for the NORR.展开更多
Developing Cu single-atom catalysts(SACs)with well-defined active sites is highly desirable for producing CH4 in the electrochemical CO_(2)reduction reaction and understanding the structure-property relationship.Herei...Developing Cu single-atom catalysts(SACs)with well-defined active sites is highly desirable for producing CH4 in the electrochemical CO_(2)reduction reaction and understanding the structure-property relationship.Herein,a new graphdiyne analogue with uniformly distributed N2-bidentate(note that N2-bidentate site=N^N-bidentate site;N2¹dinitrogen gas in this work)sites are synthesized.Due to the strong interaction between Cu and the N2-bidentate site,a Cu SAC with isolated undercoordinated Cu-N2 sites(Cu1.0/N2-GDY)is obtained,with the Cu loading of 1.0 wt%.Cu1.0/N2-GDY exhibits the highest Faradaic efficiency(FE)of 80.6%for CH4 in electrocatalytic reduction of CO_(2)at-0.96 V vs.RHE,and the partial current density of CH4 is 160 mA cm^(-2).The selectivity for CH4 is maintained above 70%when the total current density is 100 to 300 mA cm^(-2).More remarkably,the Cu1.0/N2-GDY achieves a mass activity of 53.2 A/mgCu toward CH4 under-1.18 V vs.RHE.In situ electrochemical spectroscopic studies reveal that undercoordinated Cu-N2 sites are more favorable in generating key*COOH and*CHO intermediate than Cu nanoparticle counterparts.This work provides an effective pathway to produce SACs with undercoordinated Metal-N2 sites toward efficient electrocatalysis.展开更多
基金supported by the National Natural Science Foundation of China(2113301121203221+1 种基金21473224)the Natural Science Foundation of Gansu Province(1308RJZA281)~~
文摘Cu nanoparticles supported on a variety of oxide supports, including SiO2, TiO2, ZrO2, Al2O3, MgO and ZnO, were investigated for the hydrogenolysis of biomass‐derived furfuryl alcohol to1,2‐pentanediol and 1,5‐pentanediol. A Cu‐Al2O3 catalyst with 10 wt% Cu loading prepared by a co‐precipitation method exhibited the best performance in terms of producing pentanediols compared with the other materials. This catalyst generated an 85.8% conversion and a 70.3% combined selectivity for the target pentanediols at 413 K and 8 MPa H2 over an 8‐h reaction. The catalyst could also be recycled over repeated reaction trials without any significant decrease in productivity. Characterizations with X‐ray diffraction, NH3/CO2‐temperature programmed desorption, N2 adsorption,transmission electron microscopy and N2 O chemisorption demonstrated that intimate and effective interactions between Cu particles and the acidic Al2O3 support in this material greatly enhanced its activity and selectivity. The promotion of the hydrogenolysis reaction was found to be especially sensitive to the Cu particle size, and the catalyst with Cu particles 1.9 to 2.4 nm in size showed the highest turnover frequency during the synthesis of pentanediols.
基金Project(738010004)supported by the Project of Low Concentration Sulfur Dioxide Flue Gas Treatment,ChinaProject(2017GK4010)supported by the Scientific and Technological Breakthrough and Major Achievements Transformation of Strategic Emerging Industries of Hunan Province in 2017,China
文摘Using Cu-BTC prepared by hydrothermal method as precursor, carbon-based catalysts were obtained as model materials for low-temperature DeNO_x. These catalysts were characterized by X-ray diffractometry（XRD）, Raman spectroscopy, scanning electron microscopy（SEM） and energy dispersive X-ray spectrometry（EDS）. The results showed that all carbon-based catalysts held the octahedron shape of Cu-BTC in most parts, and they mainly consisted of face-centered cubic copper. CuO_x/C exhibited excellent catalytic activity, and such catalytic activity was further improved with the introduction of Ag. The catalyst with a Cu to Ag mole ratio of 6：1 and an activated temperature of 600 °C showed the best catalytic performance, and its catalytic denitration rate reached 100% at a temperature as low as 235 °C. During the catalytic reaction process, Cu~＋ mainly played a catalytic role.
文摘Cu-based catalysts are commonly used in industry for methanol synthesis.In this study,supported catalysts of 5 wt%Cu/Al_(2)O_(3)and 5 wt%Cu/ZnO were prepared,and their surface characteristics during H_(2) reduction and CO_(2)hydrogenation were investigated using in situ Fourier transform infrared spectroscopy(FTIR),ex situ X-ray photoelectron spectroscopy,and high sensitivity low energy ion scattering spectroscopy.During the H2 reduction and CO_(2)hydrogenation processes,it was found that Al_(2)O_(3)can stabilize Cu^(+).In situ FTIR spectra indicated that the 5 wt%Cu/Al_(2)O_(3)can adsorb large amounts of bicarbonate and carbonate species,which then convert into formate during CO_(2)hydrogenation.For the 5 wt%Cu/ZnO,it was found that Cu nanoparticles were gradually covered by a highly defective ZnOx overlayer during H2 reduction,which can effectively dissociate H2.During CO_(2)hydrogenation,the adsorbed bicarbonate or carbonate species can convert into formate and then into a methoxy species.Using these surface sensitive methods,a more in-depth understanding of the synergistic effect among the Cu,Al_(2)O_(3),and ZnO components of Cu-based catalysts was achieved.
基金supported by the National Natural Science Foundation of China(Nos.21907043 and 21801153)Shandong Provincial Natural Science Foundation(No.ZR2019BB025).
文摘Electroreduction of greenhouse gas CO_(2) into value-added fuels and chemicals provides a promising pathway to address the issues of energy crisis and environmental change.However,the regulations of the selectivity towards C2 product and the competing hydrogen evolution reaction(HER)are major challenges for CO_(2) reduction reaction(CO_(2)RR).Here,we develop an interface-enhanced strategy by depositing a thin layer of nitrogen-doped graphene(N-G)on a Cu foam surface(Cu-N-G)to selectively promote the ethanol pathway in CO_(2)RR.Compared to the undetectable ethanol selectivity of pure Cu and Cu@graphene(Cu-G),Cu-N-G has boosted the ethanol selectivity to 33.1%in total Faradic efficiency(FE)at−0.8 V vs.reversible hydrogen electrode(RHE).The experimental and density functional theory(DFT)results verify that the interconnected graphene coating can not only serve as the fast charge transport channel but also provide confined nanospace for mass transfer.The N doping can not only trigger the intrinsic interaction between N in N-G and CO_(2) molecule for enriching the local concentration of reactants but also promote the average valence state of Cu for C–C coupling pathways.The confinement effect at the interface of Cu-N-G can not only provide high adsorbed hydrogen(Had)coverage but also stabilize the key*HCCHOH intermediate towards ethanol pathway.The provided interface-enhanced strategy herein is expected to inspire the design of Cubased CO_(2)RR electrocatalysts towards multi-carbon products.
基金supported by the National Natural Science Foundation of China(Nos.22278020,2177060378)the Program for Changjiang Scholars,Innovative Research Teams in Universities(No.IRT1205)the Fundamental Research Funds for the Central Universities(Nos.12060093063,XK1803-05).
文摘Electrocatalytic CO_(2) reduction reaction(ECO_(2)RR)converts CO_(2) to high-value chemical products and promotes the carbon cycle.Sulfur(S)-modified copper(Cu)and bismuth(Bi)-based catalysts have been recognized as promising catalysts for ECO_(2)RR.Both of them are highly active for selective formate generation,however,their poor stability and severe competing hydrogen evolution reaction(HER)remain challenging.Herein,S-doped Cu coated with Bi(Bi/Cu-S)is developed to improve ECO_(2)RR selectivity to formate.Bi/Cu-S/brass mesh(BM)electrode material for ECO_(2)RR was prepared by electrodepositing Bi on the surface of Cu-S/BM nanowires obtained from CuS/BM after the electroreduction.The Faradaic efficiency(FE)of the formate reaches the maximum of 94.3%at-0.9 V vs.reversible hydrogen electrode(RHE)with a partial current density as high as-50.7 mA·cm^(-2) and a yield of 30.7 mmol·h^(-1)·cm^(-2) under 0.5 M KHCO_(3) electrolyte.Meanwhile,the FE of formate is higher than 90%in the voltage range of-0.8 to-1.0 V vs.RHE.It also shows good stability at-0.9 V vs.RHE with the FE of formate remaining above 93%after a 10 h reaction.Density functional theory(DFT)calculations demonstrate that the Bi/Cu-S structure promotes the adsorption of CO_(2) and effectively inhibits HER by enhancing the adsorption of^(*)H to a great extent,improving the selective conversion of CO_(2) to formate.This work deepens the understanding of the mechanism of Cu-Bi-based catalysts and S-modified Cu-based catalysts in selective ECO_(2)RR to formate,and also provides a new strategy for catalyst design.
基金supported by the National Natural Science Foundation of China(No.52161025)Fundamental Researches Top Talent Program of Lanzhou Jiaotong University(No.2022JC03).
文摘Electrochemical NO reduction reaction(NORR)to generate NH_(3)emerges as a fascinating approach to achieve both NO pollution mitigation and sustainable NH_(3)synthesis.Herein,we demonstrate that single-atomic Cu anchored on MoS_(2)(Cu_(1)/MoS_(2))comprising Cu_(1)-S_(3)motifs can serve as a highly efficient NORR catalyst.Cu1/MoS_(2)exhibits an NH_(3)yield rate of 337.5μmol·h^(−1)·cm^(−2)with a Faradaic efficiency of 90.6%at−0.6 V vs.reversible hydrogen electrode(RHE).Combined experiments and theoretical calculations reveal that Cu1-S3 motifs enable the effective activation and hydrogenation of NO through a mixed pathway and simultaneously retard proton coverage,contributing to the high activity and selectivity of Cu1/MoS_(2)for the NORR.
文摘Developing Cu single-atom catalysts(SACs)with well-defined active sites is highly desirable for producing CH4 in the electrochemical CO_(2)reduction reaction and understanding the structure-property relationship.Herein,a new graphdiyne analogue with uniformly distributed N2-bidentate(note that N2-bidentate site=N^N-bidentate site;N2¹dinitrogen gas in this work)sites are synthesized.Due to the strong interaction between Cu and the N2-bidentate site,a Cu SAC with isolated undercoordinated Cu-N2 sites(Cu1.0/N2-GDY)is obtained,with the Cu loading of 1.0 wt%.Cu1.0/N2-GDY exhibits the highest Faradaic efficiency(FE)of 80.6%for CH4 in electrocatalytic reduction of CO_(2)at-0.96 V vs.RHE,and the partial current density of CH4 is 160 mA cm^(-2).The selectivity for CH4 is maintained above 70%when the total current density is 100 to 300 mA cm^(-2).More remarkably,the Cu1.0/N2-GDY achieves a mass activity of 53.2 A/mgCu toward CH4 under-1.18 V vs.RHE.In situ electrochemical spectroscopic studies reveal that undercoordinated Cu-N2 sites are more favorable in generating key*COOH and*CHO intermediate than Cu nanoparticle counterparts.This work provides an effective pathway to produce SACs with undercoordinated Metal-N2 sites toward efficient electrocatalysis.
