Highly Dispersed Nickel Phthalocyanine on Nitrogen-Doped Three-Dimensional Porous Carbon for Efficient Electrocatalytic CO₂ Reduction

Electrocatalytic carbon dioxide reduction reaction (CO2RR) effectively mitigates CO2 emissions, addressing global warming and climate change. In this study, nitrogen-doped three-dimensional porous carbon materials (RMF) were synthesized using a silica template-mediated method combined with in situ nitrogen doping. The resulting carrier, with a well-developed pore structure and tunable nitrogen content, enables the uniform dispersion of nickel phthalocyanine (NiPc) molecular catalysts, optimizing their coordination. The catalyst maintains a residual pore structure that enhances gas diffusion and exposes catalytic sites. Carbon-based catalysts with varying nitrogen doping levels exhibit differences in microstructure and electrochemical properties. Notably, the NiPc/RMF1 catalyst, with optimal nitrogen content, shows a faradaic efficiency of 92.0% for carbon monoxide (CO) production at −0.83 voltage vs reversible hydrogen electrode (V vs RHE), and a current density of 9.7 mA cm–2 in 0.5 M KHCO3 electrolyte saturated with CO2. In situ FTIR spectroscopy confirmed that NiPc influenced by porous nitrogen-doped carbon facilitates the faster formation of the *COOH intermediate. DFT calculations further revealed that the superior performance of NiPc/RMF1 is attributed to the reduced energy barrier in CO2RR. This synthesis strategy provides a useful guide for preparing supported molecular catalysts.