Rational design of nitrogen-doped porous carbon support on single atom catalysts for efficient CO2 electroreduction

Nitrogen-coordinated single metal atoms supported on carbon (M-Nx/C) catalysts exhibit remarkable activities during the electrochemical CO2 reduction reaction (CO2RR). However, exploring the relationship between the support properties, such as morphology and electron conductivity, and catalytic activity remains challenging because conventional high-temperature pyrolysis induces multiple M-Nx coordination in the M-Nx/C catalysts. Herein, a series of nitrogen-doped porous carbon supports with various pore sizes and degrees of graphitization were prepared, and Ni-N4 active sites were subsequently loaded by anchoring Ni phthalocyanine (NiPc). We found that the electron conductivity of the support is crucial for enhancing the CO selectivity in the low-potential region (from -0.5 to -0.7 VRHE). However, effective CO2 transport, which is strongly affected by the morphology of the support, has a more dominant effect than electron conductivity on catalytic activity. The optimized catalyst exhibits outstanding CO2RR performances owing to the presence of mesoporous graphitic carbon and nitrogen in the supports, compared with 2D graphene without mesopores and mesoporous graphitic carbon supports without nitrogen.