Facile Synthesis of Hierarchically Porous Ni-N-C for Efficient CO₂ Electroreduction to CO

The reasonable design of atomically dispersed Ni-N sites in porous carbon nanostructures is an efficient strategy to enhance the electrochemical CO₂ reduction reaction (CO₂RR) catalytic activity. In this work, atomically dispersed Ni-N sites on hierarchically porous carbon catalysts (HP-Ni-NC) were fabricated by a facile NaCl template-assisted pyrolysis method. The catalysts exhibit a large specific surface area and a hierarchical porous structure, facilitating the exposure of numerous active sites and the mass/electron transport during the CO₂RR. Consequently, the CO Faradaic efficiency maintained over 90% in a wide potential window on the optimized HP-Ni-NC-2 catalyst. The CO partial current achieved 15.2 mA cm^-2 at -0.9 V (vs reversible hydrogen electrode) in a H-cell. Furthermore, the current density can achieve 250 mA cm^-2 at a cell voltage of 3.11 V in a membrane electrode assembly electrolyzer, demonstrating great promise for commercial-scale application. This study presents a facile approach to synthesizing hierarchically porous structure single-atom catalysts with superior catalytic performance toward CO₂RR.