Layer-by-layer enriching active Ni-N3C sites in nickel-nitrogen-carbon electrocatalysts for enhanced CO2-to-CO reduction |
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| Institution: | 1. State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials, Liaoning Key Laboratory for Catalytic Conversion of Carbon Resources, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China;2. Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, China;1. School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013, China;2. School of Resource and Environmental Engineering, Jilin Institute of Chemical Technology, Jilin 132000, China;1. College of Environmental Science and Engineering, Central South University of Forestry and Technology, Changsha 410004, China;2. School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States;3. Georgia Tech Shenzhen Institute, Tianjin University, Shenzhen 518067, China |
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| Abstract: | Transition metal and nitrogen co-doped carbons (M-N-C) have proven to be promising catalysts for CO2 electroreduction into CO because of the high activity and selectivity. Effective enrichment of the active transition metal coordinated nitrogen sites is desirable but is challenging for a practical volumetric productivity. Herein, we report four kinds of model electrocatalysts to unveil this issue, which include the NC structures with surface N-functionalities, Ni-N-C_I with one layer of surface Ni-N3C sites, NC@Ni-N-C_I with surface N-functionalities and underneath Ni-N3C sites as well as Ni-N-C_II with doubled surface Ni-N3C sites. The X-ray absorption spectroscopy indicates the coordination configuration of Ni-N3C. For NC catalysts, when N-doping level increased from 3.5 at% to 8.4 at%, the CO partial current density increased from below 0.1 mA/cm2 to 3 mA/cm2. Introducing one layer of Ni-N3C onto the NC structures leads to a 54 times higher CO partial current density than that of NC, in the meantime the FECO is 66 times higher. Furthermore, doubling the density of surface Ni-N3C sites by a layer-by-layer method doubles the CO partial current density (jCO), indicating its potential to achieve a high density of active coordinated sites and current densities. |
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