Electroreduction of CO₂ to CO on a Mesoporous Carbon Catalyst with Progressively Removed Nitrogen Moieties

In this study, we prepared nitrogen-removed mesoporous carbon (NRMC) catalysts by applying various heat treatments to nitrogen-doped mesoporous carbon (NMC), which were applied as novel electrocatalysts for CO2 reduction reaction (CO2RR). With the nitrogen moieties being progressively removed, the NRMC catalysts exhibited enhanced CO generation from CO2RR, whereas the competing hydrogen evolution reaction (HER) has been suppressed. Through suitable annealing treatment, the defect-rich NRMC catalyst is able to convert CO2 to CO with a Faradaic efficiency (FECO) of ∼80% and a partial current density for CO (jCO) of −2.9 mA cm–2 at an applied overpotential of 490 mV. Density functional theory (DFT) calculations further revealed the active sites within NRMC catalysts were the defects generated by N removal, which lowered the energy barriers for CO2RR and will not be passivated by hydrogen. These findings provide design guidelines to develop efficient carbon-based catalysts that can display metal-like, and even better, performances for potential scalable CO2RR to fuels and chemicals.