Regulation of Ni Single-Atom/Nanoparticle Cooperative Catalytic Systems by P Heteroatom Asymmetric Coordination for Efficient Electrocatalytic CO2 Reduction

Earth-abundant transition-metal-based single-atom catalysts and nanoparticulate catalysts exhibit relatively high performance for the electrocatalytic CO₂ reduction reaction (eCO₂RR). However, the localized orbital structures of active sites of single-atom catalysts make it difficult to effectively couple key intermediates, thereby limiting their catalytic performance. Nanoparticulate catalysts are prone to aggregation during the eCO₂RR, leading to an unwanted hydrogen evolution reaction. In response to these problems, a porous carbon catalyst with Ni─N─P ternary co-doping through a two-step pyrolysis process is prepared. Ni nanoparticles (NPs) are encapsulated in the carbon support and atomically dispersed Ni single atoms (SAs) are anchored to the carbon support surface. The internal Ni─NPs provide electrons for the surface Ni─SAs, thereby helping enhance the electron-transfer efficiency. The doping element P not only tailors the sizes of Ni─NPs, suppressing their hydrogen evolution activity but also forms the asymmetric NiN₃P─SA active sites, enhancing the coupling strength between the catalyst and adsorbed intermediates. Given the unique structural features, this porous Ni─N─P ternary co-doped coal-based catalyst achieves increased CO selectivity (95%), current density (227.4 mA cm⁻²) and stability (120 h).