Theoretical study of transition metal-doped β 12 borophene as a new single-atom catalyst for carbon dioxide electroreduction.

The electrocatalytic carbon dioxide reduction reaction (CO 2 RR) presents a viable and cost-effective approach for the elimination of CO 2 by transforming it into valuable products. Nevertheless, this process is impeded by the absence of exceptionally active and stable catalysts. Herein, a new type of electrocatalyst of transition metal (TM)-doped β 12 -borophene (TM@β 12 -BM) is investigated via density functional theory (DFT) calculations. Through comprehensive screening, two promising single-atom catalysts (SACs), Sc@β 12 -BM and Y@β 12 -BM, are successfully identified, exhibiting high stability, catalytic activity and selectivity for the CO 2 RR. The C 1 products methane (CH 4 ) and methanol (CH 3 OH) are synthesized with limiting potentials ( U L ) of -0.78 V and -0.56 V on Sc@β 12 -BM and Y@β 12 -BM, respectively. Meanwhile, CO 2 is more favourable for reduction into the C 2 product ethanol (CH 3 CH 2 OH) compared to ethylene (C 2 H 4 ) via C-C coupling on these two SACs. More importantly, the dynamic barriers of the key C-C coupling step are 0.53 eV and 0.73 eV for the "slow-growth" sampling approach in the explicit water molecule model. Furthermore, Sc@β 12 -BM and Y@β 12 -BM exhibit higher selectivity for producing C 1 compounds (CH 4 and CH 3 OH) than C 2 (CH 3 CH 2 OH) in the CO 2 RR. Compared with Sc@β 12 -BM, Y@β 12 -BM demonstrates superior inhibition of the competitive hydrogen evolution reaction (HER) in the liquid phase. These results not only demonstrate the great potential of SACs for direct reduction of CO 2 to C 1 and C 2 , but also help in rationally designing high-performance SACs.