Cu-based catalysts are widely employed for CO_(2) hydrogenation to methanol,which is expected as a promising process to achieving carbon neutrality.However,most Cu-based catalysts still suffer from low methanol yield ...Cu-based catalysts are widely employed for CO_(2) hydrogenation to methanol,which is expected as a promising process to achieving carbon neutrality.However,most Cu-based catalysts still suffer from low methanol yield with a passable CO_(2) conversion and lack insight into its reaction mechanism for guiding the design of catalysts.In this work,Cu^(+)/CeZrO_(x) interfaces are engineered by employing a series of ceria-zirconia solid solution catalysts with various Ce/Zr ratios,forming a Cu^(+)-O_(v)-Ce^(3+)structure where Cu^(+)atoms are bonded to the oxygen vacancies(O_(v))of ceria.Compared to Cu/CeO_(2) and Cu/ZrO_(2),the optimized catalyst(i.e.,Cu_(0.3)Ce_(0.3)Zr_(0.7))exhibits a much higher mass-specific methanol formation rate(192g_(MeOH)/kg_(cat)/h)at 240℃and 3 MPa.Through a series of in-situ and ex-situ characterization,it is revealed that oxygen vacancies in solid solutions can effectively assist the activation of CO_(2) and tune the electronic state of copper to promote the formation of Cu^(+)/CeZrO_(x) interfaces,which stabilizes the key*CO intermediate,inhibits its desorption and facilitates its further hydrogenation to methanol via the reverse watergas-shift(RWGS)+CO-Hydro pathway.Therefore,the concentration of*CO or the apparent Cu^(+)/(Cu^(+)+Cu^(0))ratio could be employed as a quantitative descriptor of the methanol formation rate.This work is expected to give a deep insight into the mechanism of metal/support interfaces in CO_(2) hydrogenation to methanol,offering an effective strategy to develop new catalysts with high performance.展开更多
Electrocatalytic CO_(2)reduction reaction(CO_(2)RR)to produce multicarbon(C_(2+))products over Cubased catalysts represents an ideal approach for renewable energy storage and carbon emissions reduction.The Cu^(0)/Cu^(...Electrocatalytic CO_(2)reduction reaction(CO_(2)RR)to produce multicarbon(C_(2+))products over Cubased catalysts represents an ideal approach for renewable energy storage and carbon emissions reduction.The Cu^(0)/Cu^(δ+)interfaces are widely recognized as crucial sites that promote C-C coupling and enhance the generation of C2+products.However,a major challenge arises from the tendency of Cu^(δ+)active sites within Cu^(0)/Cu^(δ+)interfaces to undergo reduction to Cu^(0)during the CO_(2)RR process,leading to a decline in catalytic performance.Hence,it is crucial to establish durable Cu^(0)/Cu^(δ+)interfaces to enhance the conversion of CO_(2)to C_(2+)products.In this work,an iodine modification strategy is proposed to prepare a stable Cu@CuI composite catalyst with well-maintained Cu^(0)/Cu^(δ+)interfaces through a one-step redox reaction between iodine and copper.The optimized Cu@CuI-3composite catalyst demonstrates an excellent performance in CO_(2)RR,achieving a Faradaic efficiency of 75.7%for C^(2+)products and a partial current density of 288 mA·cm^(-2)at-1.57 V_(RHE)in a flow cell.Operando techniques reveal that a numerous persistent Cu^(δ+)species exist on the surface of the Cu@CuI-X composite catalyst even after CO_(2)RR due to the presence of adsorbed iodine ions,which prevent complete reduction of Cu^(δ+)species to Cu^(0)owing to their high electronegativity.Density functional theory calculations further verify that adsorbed iodine ions on the surface of Cu@CuI-X serve as charge regulators by adjusting local charge density,thereby facilitating the formation of*CHO intermediates from CO_(2)and lowering the energy barriers associated with coupling the*CHO and*CO intermediates during CO_(2)RR.Consequently,this phenomenon enhances the selectivity toward C_(2+)products during electrocatalytic CO_(2)reduction.展开更多
基金sponsored by the National Natural Science Foundation of China(21808120,21978148)。
文摘Cu-based catalysts are widely employed for CO_(2) hydrogenation to methanol,which is expected as a promising process to achieving carbon neutrality.However,most Cu-based catalysts still suffer from low methanol yield with a passable CO_(2) conversion and lack insight into its reaction mechanism for guiding the design of catalysts.In this work,Cu^(+)/CeZrO_(x) interfaces are engineered by employing a series of ceria-zirconia solid solution catalysts with various Ce/Zr ratios,forming a Cu^(+)-O_(v)-Ce^(3+)structure where Cu^(+)atoms are bonded to the oxygen vacancies(O_(v))of ceria.Compared to Cu/CeO_(2) and Cu/ZrO_(2),the optimized catalyst(i.e.,Cu_(0.3)Ce_(0.3)Zr_(0.7))exhibits a much higher mass-specific methanol formation rate(192g_(MeOH)/kg_(cat)/h)at 240℃and 3 MPa.Through a series of in-situ and ex-situ characterization,it is revealed that oxygen vacancies in solid solutions can effectively assist the activation of CO_(2) and tune the electronic state of copper to promote the formation of Cu^(+)/CeZrO_(x) interfaces,which stabilizes the key*CO intermediate,inhibits its desorption and facilitates its further hydrogenation to methanol via the reverse watergas-shift(RWGS)+CO-Hydro pathway.Therefore,the concentration of*CO or the apparent Cu^(+)/(Cu^(+)+Cu^(0))ratio could be employed as a quantitative descriptor of the methanol formation rate.This work is expected to give a deep insight into the mechanism of metal/support interfaces in CO_(2) hydrogenation to methanol,offering an effective strategy to develop new catalysts with high performance.
基金financially supported by the National Natural Science Foundation of China(Nos.52073009,52272182,51872013 and 52011530190)the Program of the Ministry of Education of China for Introducing Talents of Discipline to Universities(No.B14009)。
文摘Electrocatalytic CO_(2)reduction reaction(CO_(2)RR)to produce multicarbon(C_(2+))products over Cubased catalysts represents an ideal approach for renewable energy storage and carbon emissions reduction.The Cu^(0)/Cu^(δ+)interfaces are widely recognized as crucial sites that promote C-C coupling and enhance the generation of C2+products.However,a major challenge arises from the tendency of Cu^(δ+)active sites within Cu^(0)/Cu^(δ+)interfaces to undergo reduction to Cu^(0)during the CO_(2)RR process,leading to a decline in catalytic performance.Hence,it is crucial to establish durable Cu^(0)/Cu^(δ+)interfaces to enhance the conversion of CO_(2)to C_(2+)products.In this work,an iodine modification strategy is proposed to prepare a stable Cu@CuI composite catalyst with well-maintained Cu^(0)/Cu^(δ+)interfaces through a one-step redox reaction between iodine and copper.The optimized Cu@CuI-3composite catalyst demonstrates an excellent performance in CO_(2)RR,achieving a Faradaic efficiency of 75.7%for C^(2+)products and a partial current density of 288 mA·cm^(-2)at-1.57 V_(RHE)in a flow cell.Operando techniques reveal that a numerous persistent Cu^(δ+)species exist on the surface of the Cu@CuI-X composite catalyst even after CO_(2)RR due to the presence of adsorbed iodine ions,which prevent complete reduction of Cu^(δ+)species to Cu^(0)owing to their high electronegativity.Density functional theory calculations further verify that adsorbed iodine ions on the surface of Cu@CuI-X serve as charge regulators by adjusting local charge density,thereby facilitating the formation of*CHO intermediates from CO_(2)and lowering the energy barriers associated with coupling the*CHO and*CO intermediates during CO_(2)RR.Consequently,this phenomenon enhances the selectivity toward C_(2+)products during electrocatalytic CO_(2)reduction.
基金supported by the National Key Research and Development Project(2018YFB1502401 and 2018YFA0702002)the Program for Changjiang Scholars and Innovation Research Team in the University(IRT1205)+1 种基金the Fundamental Research Funds for the Central Universitiesthe long-term subsidy mechanism from the Ministry of Finance and the Ministry of Education of China。
