Synthesizing MOF-derived NiNC catalyst via surfactant modified strategy for efficient electrocatalytic CO₂ to CO

Recently, Ni, N-doped carbon (NiNC) electrocatalysts synthesized using metal-organic frameworks (MOFs) as templates have demonstrated attractive catalytic performances in the CO₂ reduction reaction (CO₂RR). However, most of the reported preparations of MOFs-based precursors are carried out in organic solvents, and the resulting NiNC materials have relatively low metal loadings and mainly exhibit microporous structures, which is unfavorable for the mass transport. Herein, Ni, N-doped meso-microporous carbon electrocatalysts with a range of Ni loadings (M-NiNCx/CNTs) were prepared by the pyrolysis of MOFs-based precursors synthesized in aqueous solution using the surfactant cetyltrimethylammonium bromide (CTAB) as a modifier to promote the adsorption of Ni²⁺ ions and the formation of mesopores. Owing to the unique morphology, porous structure and high contents of Ni-N_x sites and pyrrolic-N, the optimal catalyst (M-NiNC2/CNTs) shows superior electrocatalytic activity for the CO₂RR with a maximum CO Faradaic efficiency (FE_CO) of 98 % at -0.7 V vs. reversible hydrogen electrode (RHE), and the FE_CO can reach over 80 % in a wide potential range of -0.5 to -1.0 V vs. RHE. This work develops a facile and environmentally friendly strategy to obtain high-performance and low-cost transition metal-nitrogen-doped porous carbon electrocatalysts for the CO₂RR.