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 (CO2 RR) presents a viable and cost-effective approach for the elimination of CO2 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 β12 -borophene (TM@β12 -BM) is investigated via density functional theory (DFT) calculations. Through comprehensive screening, two promising single-atom catalysts (SACs), Sc@β12 -BM and Y@β12 -BM, are successfully identified, exhibiting high stability, catalytic activity and selectivity for the CO2 RR. The C1 products methane (CH4 ) and methanol (CH3 OH) are synthesized with limiting potentials ( U L ) of -0.78 V and -0.56 V on Sc@β12 -BM and Y@β12 -BM, respectively. Meanwhile, CO2 is more favourable for reduction into the C2 product ethanol (CH3 CH2 OH) compared to ethylene (C2 H4 ) 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@β12 -BM and Y@β12 -BM exhibit higher selectivity for producing C1 compounds (CH4 and CH3 OH) than C2 (CH3 CH2 OH) in the CO2 RR. Compared with Sc@β12 -BM, Y@β12 -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 CO2 to C1 and C2 , but also help in rationally designing high-performance SACs.