Electrochemical CO2 reduction on metal-silicon centered single-atom dual site catalyst: A computational study

In this work, we employed density functional theory (DFT) computations to design innovative electrocatalysts for the electrochemical CO2 reduction reaction (ECRR). Specifically, we focused on single-metal dual site catalysts (SM-DSCs) based on monolayer boron nitride (BN) modified with silicon (Si) or carbon (C) coordinating atoms. These materials, denoted as M@BN_D(V) (BN = boron nitride monolayer; D = Si or C atom; M = metal atoms; V = B vacancy or N vacancy), were investigated as the potential electrocatalysts for the ECRR. Our computational results revealed that Fe@BN_Si(B) and Fe@BN_C(N) were the most stable forms for Fe@BN_Si(V) and Fe@BN_C(V), respectively. After that, we proceeded to analyze CO2 adsorption as well as reduction pathways for the ECRR based on the calculated Gibbs energy and the competitive hydrogen evolution reaction (HER). Among the Fe-based catalysts, Fe@BN_Si(B) exhibited a lower limiting potential (UL) of –0.63 V, while Fe@BN_C(N) required a higher UL of –0.72 V for the production of CH4(g). Notably, both Fe@BN_Si(B) and Fe@BN_C(N) catalysts displayed high selectivity compared to the HER. Accordingly, Fe@BN_Si(B) and Fe@BN_C(N) catalysts are emerged as the promising electrocatalyst candidates for the ECRR. In addition, the UL required to overcome was reduced to –0.35 V for WFe@BN_Si(B) in a water co-adsorption environment, suggesting the catalytic performance can be enhanced by water promotion effect.