Theoretical insights into p-block-functionalized carbon edges for efficient electrochemical CO2 reduction

Abstract

Metal-free carbon materials are promising catalysts for the electrochemical CO₂ reduction reaction (CO₂RR). However, the principles for regulating carbon materials still require further discussion. In this context, p-block elements with varying electronegativity may offer extensive opportunities for modulating the electronic properties of the active sites. Herein, density functional theory (DFT) calculations are performed on carbon materials functionalized with p-block elements to reveal their key role in the CO₂RR. We systematically screened 14 graphene nanoribbon edge models functionalized with different p-block functional groups (Edge-X/C). The results indicate that the electronegativity of the functional groups serves as a key parameter, which effectively tunes both the p-band center and the surface work function of the carbon atoms. Furthermore, a volcano-shaped relationship was observed between the p-band center and catalytic activity. This indicates that moderate orbital energy levels suppress excessive electron back-donation and promote CO desorption, which are beneficial for the CO₂RR. Edge-AsH₂/C exhibits the lowest theoretical limiting potential due to the moderate p-band center of its active sites. These insights provide a robust framework for the rational design of high-performance, metal-free electrocatalysts.