Theoretical study of transition metal-doped β₁₂ borophene as a new single-atom catalyst for carbon dioxide...

The electrocatalytic carbon dioxide reduction reaction (CO₂RR) 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 CO₂RR. The C₁ products methane (CH₄) and methanol (CH₃OH) 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 (CH₃CH₂OH) compared to ethylene (C₂H₄) 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 CH₃OH) than C₂ (CH₃CH₂OH) in the CO₂RR. 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.