Exploring reaction mechanisms for CO2 reduction on carbides†

Abstract

The electrocatalytic conversion of carbon dioxide (CO₂) into valuable fuels offers immense promise in pursuing sustainable energy solutions. Transition metal carbides (TMCs) with their robustness and intriguing electronic properties have traditionally emerged as captivating contenders in the quest for efficient catalysts for the CO₂ reduction reaction (CO₂RR). The presence of carbon atoms in TMC structures unlocks a unique reaction mechanism for the CO₂RR, namely the Mars–van Krevelen (MVK) mechanism, facilitating CO₂ capture and more efficient conversion to high-value-added chemicals. This work is the first report on the use of TMCs for the CO₂RR where comprehensive reaction pathways for different product formations are investigated. This theoretical study delves into the electronic intricacies of TMCs, unraveling their potential to drive the transformative journey toward a greener tomorrow. Here, we analyzed 11 TMCs to explore the reactivity trends toward CO, formic acid, methane, methanediol, and methanol formation. VC is the best candidate explored to produce formic acid at 0 V onset potential. In addition, WC is the best candidate explored to produce methanol at an onset potential of −0.36 V. These results demonstrate that our studied TMCs as electrocatalysts are more promising than previously studied materials (metals and oxides) for application in the CO₂RR, and thus require more attention and investigation.