Bifunctional diatomic site catalysts supported by β12-borophene for efficient oxygen evolution and reduction reactions

Efficient bifunctional catalysts for oxygen evolution and reduction reactions (OERs/ORRs) are of great importance for sustainable and renewable clean energy, especially for metal-air batteries. Herein, we investigated beta(12)-borophene with double-hole sites capped with 3d transition metal atoms to explore its catalyst performance for hydrogen evolution reactions (HERs), OERs and ORRs. It was found that the borophene is a good platform for diatomic site catalysts (DASCs) due to their advantage of stability over the corresponding single-atom catalysts (SACs) or clusters. The HER performance of DASCs on beta(12)-BM was further improved compared to the SAC case. Furthermore, the supported FeNi DASC exhibited good catalytic performance for both OERs and ORRs, the overpotentials for which were 0.43 and 0.55 V, respectively, better than those of the corresponding supported Ni or Fe SAC due to synergistic effects. We herein propose a novel descriptor involving the Bader charges of coordinated atoms explicitly, behaving much better than the d-band center and integrated crystal orbital Hamilton population (-ICOHP) for DASCs. The synergistic effect of Fe-Ni pairs balanced the too strong binding of OH and further activated OH to achieve better catalytic performance. The results of this study can provide theoretical guidance for the design of efficient bifunctional electrocatalysts.

Automated summary

Efficient bifunctional catalysts for oxygen evolution and reduction reactions are important for clean energy applications. In this study, beta(12)-borophene with double-hole sites capped with 3d transition metal atoms was investigated for its catalytic performance in hydrogen evolution, oxygen evolution, and oxygen reduction reactions. Results showed that the borophene-based diatomic site catalysts exhibited better stability and performance compared to single-atom catalysts or clusters. The synergistic effect of Fe-Ni pairs contributed to the improved catalytic performance for both oxygen evolution and reduction reactions. A novel descriptor involving Bader charges was proposed, which showed better predictive capability for the catalyst performance.