Novel multi-functional sites in boron-based bi-atom catalysts synergistically boost C-C coupling for efficient CO electroreduction towards ethanol

The electrochemical CO reduction reaction (CORR) is faced by challenges in achieving high-value-added C 2 products due to inefficient C-C bond formation and low selectivity. Using first-principles calculations, we propose a framework for boron-based bi-atom doping into a silicene monolayer (B-X@Si) to improve CORR catalytic efficiency. Transition metal (TM)-free B-B@Si and TM-containing B-Cu@Si serve as efficient bi-atom catalysts (BACs) with low limiting potentials (−0.28 and −0.63 V) and low activation barriers for C-C coupling (0.54 and 0.53 eV). The CO* binding strength of active sites with co-adsorbed CO* species follows the order TM < B < B-TM. Remarkably, the interplay within the B-TM pair strengthens CO* adsorption, driven by increased TM involvement, as characterized by the upward shift of the d-band center of TM in B-TM@Si relative to Fermi level. The coupling kinetics depend on the reactivity of C(CHO*) and CO* fragments within the decoupled CHO-CO* intermediate. Intriguingly, hetero-B-TM@Si systems display a trade-off between stronger CHO* and weaker CO* binding compared to the moderate binding observed in homo-B-B@Si. Among the TMs, Cu appears the most appropriate partner with B; the moderate synergistic effect of the B-Cu pair resulting in the smallest augmented C-affinity (CHO*) is offset by the weakest CO* binding strength on Cu itself, ensuring rapid C-C coupling similar to that of B-B@Si. Our BACs offer unique multi-functional active sites due to participation of host atoms (Si*) adjacent to the bi-dopants; these Si-atoms stabilize adsorbates, facilitate the subsequent C-C coupling step, and protect the C-O bond for selective ethanol production. This study provides theoretical insights for the development of advanced BACs with novel multi-adsorbing sites and tailored charge redistribution that enhance CO-to-C 2 conversion. Multi-active sites and electron configurations of boron-based bi-atom catalysts doped in silicene monolayers optimize adsorption behavior and facilitate the C-C coupling process for enhancement of CO reduction towards ethanol..