MOF-derived nitrogen-doped nanoporous carbon for electroreduction of CO2 to CO: the calcining temperature effect and the mechanism

Abstract

Nitrogen-doped carbon materials are promising electrocatalysts for electroreduction of CO₂. However, the low current density and moderate faradaic efficiency of these materials limit their practical application. Here, we report the MOF-derived nitrogen-doped nanoporous carbon (NC) as a highly efficient and stable electrocatalyst for the conversion of CO₂ to CO. The NC catalysts were prepared by calcining ZIF-8 at different temperatures in argon (Ar). The catalytic performances show that the higher pyrolysis temperature result in a better CO₂ electroreduction activity of the catalysts. The NC catalyst with the best performance achieves high selectivity with 95.4% CO faradaic efficiency (FE) at −0.5 V vs. reversible hydrogen electrode (RHE). The catalyst also maintains long-term stability of 20 h operation, after which the FE of CO is still greater than 90%. The experiments show that higher pyrolysis temperature reduces the total nitrogen (N) but changes the nature and density of N defects. Density functional theory calculations reveal that higher pyrolysis temperature leads to enhanced activity by promoting the formation of low multiple pyridinic N, which provides more efficient active sites.