Cu catalysts can convert CO_(2) through an electrochemical reduction reaction into a variety of useful carbon-based products.However,this capability provides an obstacle to increasing the selectivity for a single prod...Cu catalysts can convert CO_(2) through an electrochemical reduction reaction into a variety of useful carbon-based products.However,this capability provides an obstacle to increasing the selectivity for a single product.Herein,we report a simple fabrication method for a Cu-Pd alloy catalyst for use in a membrane electrode assembly(MEA)-based CO_(2) electrolyzer for the electrochemical CO_(2) reduction reaction(ECRR)with high selectivity for CO production.When the composition of the Cu-Pd alloy catalyst was fabricated at 6:4,the selectivity for CO increased and the production of multi-carbon compounds and hydrogen is suppressed.Introducing a Cu-Pd alloy catalyst with 6:4 ratio as the cathode of the MEAbased CO_(2) electrolyzer showed a CO faradaic efficiency of 92.8%at 2.4 V_(cell).We assumed that these results contributed from the crystal planes on the surface of the Cu-Pd alloy.The phases of the Cu-Pd alloy catalyst were partially separated through annealing to fabricate a catalyst with high selectivity for CO at low voltage and C_(2)H_4 at high voltage.The results of CO-stripping testing confirmed that when Cu partially separates from the lattice of the Cu-Pd alloy,the desorption of~*CO is suppressed,suggesting that C-C coupling reaction is favored.展开更多
Ammonia production via electrochemical nitrate reduction is essential for environmental protection and the emerging hydrogen economy. Complex nitrate wastewater with a wide pH range calls for flexible catalysts with h...Ammonia production via electrochemical nitrate reduction is essential for environmental protection and the emerging hydrogen economy. Complex nitrate wastewater with a wide pH range calls for flexible catalysts with high selectivity. A high Faradaic efficiency(FE) of NH3 cannot be obtained under strong acid or alkaline conditions due to the uncontrollable adsorption energy and coverage of hydrogen species(H*) on active sites. This article describes the design and fabrication of a copper-palladium(Cu-Pd) alloy nanocrystal catalyst that inhibits H2 and nitrite generation in electrolytes with different nitrate concentrations and varied pH. The interfacial sites of Cu-Pd alloys could enhance the adsorption energy and coverage of H* while increasing the reaction rate constant of NO_(2)*-to-NO*, which achieves a rapid conversion of NO_(2)* along with a decreased FE of NO_(2)-. Under ambient conditions, optimal FE(NH3) is close to 100% at a wide pH range, with the solar-to-chemical conversion efficiency approaching 4.29%. The combination of thermodynamics and kinetics investigations would offer new insights into the reduction mechanism of NO_(2)* for further development of nitrate reduction.展开更多
The synthesis of highly uniform alloy nanocrystals with a concave feature is desirable for applications in catalysis but is an arduous task. This article proposes an initiative protocol for the fabrication of novel Cu...The synthesis of highly uniform alloy nanocrystals with a concave feature is desirable for applications in catalysis but is an arduous task. This article proposes an initiative protocol for the fabrication of novel Cu-Pd alloy nanocrystals, wherein the volume of decylamine （DA） in the reaction system was found to greatly influence the formation of different morphologies, including the tetrahedron （TH）, concave tetrahedron （CTH）, rhombohedral-tetrapod （RTP）, and tetrapod （TP）. The alloy structure of the products arises from the coordination interaction between the DA and metal ions, which affects the reduction potential of Cu and Pd species, and thus yields co-reduction. Other reaction parameters, such as the type of ligand, amount of reductant, and temperature, were also altered to study the growth mechanism, yielding consistent conclusions in the diffusion-controlled regime. As a catalyst, 48-nm Cu-Pd concave tetrahedral nanocrystals were highly active for the hydrogenation of 3-nitrostyrene and exhibited 〉99.9% chemoselectivity to C=C instead of-NO2.展开更多
Electrocatalytic reduction of CO_(2)(CO_(2)RR)to multi-electron(>2e–)products provides a green and sustainable route for producing fuels and chemicals.Introducing the second metal element is a feasible strategy fo...Electrocatalytic reduction of CO_(2)(CO_(2)RR)to multi-electron(>2e–)products provides a green and sustainable route for producing fuels and chemicals.Introducing the second metal element is a feasible strategy for"managing"the key intermediate on Cu-based materials to further improve the CO_(2)RR catalytic performance.In this work,palladium,which promises the generation of CO,was introduced into the poly(ionic liquid)-based copper hybrid(Cu@PIL)to construct a novel Cu-Pd bimetallic electrocatalyst(Cu@PIL@Pd).Remarkably,with a small dosage of palladium(2.0 mol%compared with Cu),a high faradaic efficiency(FE)for C_(2+)products(68.7%)was achieved at–1.01 V(with respect to the reversible hydrogen electrode(RHE),the same below)with a high partial current density of 178.3 mA cm^(-2).Meanwhile,high selectivity towards CH4(FE=42.5%)and corresponding partial current density of 172.8 mA cm^(-2)were obtained on the same catalyst at–1.24 V,signifying a significant potential-dependent selectivity.Mechanistic studies reveal that both copper and palladium oxides are reduced to metallic states during the CO_(2)RR.The presence of the adjoint copper phase and the highly dispersed electrostatic layer promote the generation of CO on the palladium components(both the PdO_(2)phase and the Pd(II)site).Besides,the local CO^(*)was enriched by the significant diffusion resistance of CO in the PIL layer.The spillover of CO^(*)from Pd sites to the adjoint Cu sites,accompanied by the increased local concentration of CO^(*)around Cu sites,accounted for the observed good CO_(2)RR catalytic performance,especially the high C_(2+)product selectivity.展开更多
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government MSIT(2021R1A2C2093358,2021R1A4A3027878,2022M3I3A1081901)financial support from the Lotte Chemical Company。
文摘Cu catalysts can convert CO_(2) through an electrochemical reduction reaction into a variety of useful carbon-based products.However,this capability provides an obstacle to increasing the selectivity for a single product.Herein,we report a simple fabrication method for a Cu-Pd alloy catalyst for use in a membrane electrode assembly(MEA)-based CO_(2) electrolyzer for the electrochemical CO_(2) reduction reaction(ECRR)with high selectivity for CO production.When the composition of the Cu-Pd alloy catalyst was fabricated at 6:4,the selectivity for CO increased and the production of multi-carbon compounds and hydrogen is suppressed.Introducing a Cu-Pd alloy catalyst with 6:4 ratio as the cathode of the MEAbased CO_(2) electrolyzer showed a CO faradaic efficiency of 92.8%at 2.4 V_(cell).We assumed that these results contributed from the crystal planes on the surface of the Cu-Pd alloy.The phases of the Cu-Pd alloy catalyst were partially separated through annealing to fabricate a catalyst with high selectivity for CO at low voltage and C_(2)H_4 at high voltage.The results of CO-stripping testing confirmed that when Cu partially separates from the lattice of the Cu-Pd alloy,the desorption of~*CO is suppressed,suggesting that C-C coupling reaction is favored.
基金supported by the National Key R&D Program of China(2021YFA1500804)the National Natural Science Foundation of China(22121004,51861125104)+1 种基金the Natural Science Foundation of Tianjin City(18JCJQJC47500)Haihe Laboratory of Sustainable Chemical Transformations,the Program of Introducing Talents of Discipline to Universities(BP0618007)and the Xplorer Prize.
文摘Ammonia production via electrochemical nitrate reduction is essential for environmental protection and the emerging hydrogen economy. Complex nitrate wastewater with a wide pH range calls for flexible catalysts with high selectivity. A high Faradaic efficiency(FE) of NH3 cannot be obtained under strong acid or alkaline conditions due to the uncontrollable adsorption energy and coverage of hydrogen species(H*) on active sites. This article describes the design and fabrication of a copper-palladium(Cu-Pd) alloy nanocrystal catalyst that inhibits H2 and nitrite generation in electrolytes with different nitrate concentrations and varied pH. The interfacial sites of Cu-Pd alloys could enhance the adsorption energy and coverage of H* while increasing the reaction rate constant of NO_(2)*-to-NO*, which achieves a rapid conversion of NO_(2)* along with a decreased FE of NO_(2)-. Under ambient conditions, optimal FE(NH3) is close to 100% at a wide pH range, with the solar-to-chemical conversion efficiency approaching 4.29%. The combination of thermodynamics and kinetics investigations would offer new insights into the reduction mechanism of NO_(2)* for further development of nitrate reduction.
文摘The synthesis of highly uniform alloy nanocrystals with a concave feature is desirable for applications in catalysis but is an arduous task. This article proposes an initiative protocol for the fabrication of novel Cu-Pd alloy nanocrystals, wherein the volume of decylamine （DA） in the reaction system was found to greatly influence the formation of different morphologies, including the tetrahedron （TH）, concave tetrahedron （CTH）, rhombohedral-tetrapod （RTP）, and tetrapod （TP）. The alloy structure of the products arises from the coordination interaction between the DA and metal ions, which affects the reduction potential of Cu and Pd species, and thus yields co-reduction. Other reaction parameters, such as the type of ligand, amount of reductant, and temperature, were also altered to study the growth mechanism, yielding consistent conclusions in the diffusion-controlled regime. As a catalyst, 48-nm Cu-Pd concave tetrahedral nanocrystals were highly active for the hydrogenation of 3-nitrostyrene and exhibited 〉99.9% chemoselectivity to C=C instead of-NO2.
基金Key Research Program of Frontier Sciences,CAS(ZDBS-LY-JSC022)Excellent Young Scientists Fund(22022815)+1 种基金National Natural Science Foundation of China(U1704251 and 21776291)Zhengzhou High Level Talent Certificate(20180200052)is gratefully acknowledged.
文摘Electrocatalytic reduction of CO_(2)(CO_(2)RR)to multi-electron(>2e–)products provides a green and sustainable route for producing fuels and chemicals.Introducing the second metal element is a feasible strategy for"managing"the key intermediate on Cu-based materials to further improve the CO_(2)RR catalytic performance.In this work,palladium,which promises the generation of CO,was introduced into the poly(ionic liquid)-based copper hybrid(Cu@PIL)to construct a novel Cu-Pd bimetallic electrocatalyst(Cu@PIL@Pd).Remarkably,with a small dosage of palladium(2.0 mol%compared with Cu),a high faradaic efficiency(FE)for C_(2+)products(68.7%)was achieved at–1.01 V(with respect to the reversible hydrogen electrode(RHE),the same below)with a high partial current density of 178.3 mA cm^(-2).Meanwhile,high selectivity towards CH4(FE=42.5%)and corresponding partial current density of 172.8 mA cm^(-2)were obtained on the same catalyst at–1.24 V,signifying a significant potential-dependent selectivity.Mechanistic studies reveal that both copper and palladium oxides are reduced to metallic states during the CO_(2)RR.The presence of the adjoint copper phase and the highly dispersed electrostatic layer promote the generation of CO on the palladium components(both the PdO_(2)phase and the Pd(II)site).Besides,the local CO^(*)was enriched by the significant diffusion resistance of CO in the PIL layer.The spillover of CO^(*)from Pd sites to the adjoint Cu sites,accompanied by the increased local concentration of CO^(*)around Cu sites,accounted for the observed good CO_(2)RR catalytic performance,especially the high C_(2+)product selectivity.
