Mesopore-Augmented Electrochemical CO2 Reduction on Nitrogen-Doped Carbon.

Abstract

The electrochemical carbon dioxide reduction reaction (eCO₂RR) using nitrogen-doped carbon (N-C) materials offers a promising and cost-effective approach to global carbon neutrality. Regulating the porosity of N-C materials can potentially increase the catalytic performance by suppressing the concurrence of the hydrogen evolution reaction (HER). However, the augmentation of porosity usually alters the active sites or the chemical composition of catalysts, resulting in intertwined influences of various structural factors and catalytic performance. In this study, incorporating secondary carbon sources into the metal-organic framework (MOF) precursor through nanocasting aimed to selectively enhance the mesoporous structure, allowing for deciphering this effect from other changes in the catalyst composition. Consequently, the developed N-C catalyst exhibited a significant surface area with abundant mesopores, leading to a maximum Faradaic efficiency (FE) for carbon monoxide (CO) of 95% at -0.50 V versus the reversible hydrogen electrode (vs. RHE). Furthermore, the FE for CO is enhanced across a wide potential range, surpassing previously reported metal-free N-C eCO₂RR catalysts. The investigation reveals that constructing mesoporous structures can induce excellent CO₂ catalysis by enhancing the accessibility of active sites while establishing an elevated local pH at these sites.