Mo_4/3B₂O₂-supported single-atom catalysts for oxygen reduction reaction

Exploring earth-abundant and inexpensive electrocatalysts to realize efficient oxygen reduction reaction (ORR) is urgently desired. In this work, through first-principles calculations, we have strategically designed a series of single-atom catalysts (SACs) for ORR by immobilizing single atoms on the surface of Mo_4/3B₂O₂, denoted as TM@Mo_4/3B₂O₂ (TM representing 3d, 4d, and 5d transition metal atoms, excluding Tc and Hg). Significantly, for 4e⁻ ORR, the best catalyst was Co@Mo_4/3B₂O₂ and Ru@Mo_4/3B₂O₂, with an overpotential of 0.61 V and 0.63 V, close to the commonly used Pt catalyst (0.45 V). In 2e⁻ ORR, Zn@Mo_4/3B₂O₂ had the best catalytic activity, with a ΔG_*OOH of -2.47 eV, close to the commonly used Pd catalyst (ΔG_*OOH = -3.17 eV). By calculating the electronic properties of SACs, it was found that the number of electrons gained by the intermediate *O₂ and *OOH from the SACs determines the O₂ adsorption structures and ORR reaction pathways. In addition, there are two descriptors: ICOHP and a composition descriptor which provides atomic-level insights, that were found to summarize the ORR activity rules. Our work enriches the applications of the MBenes family in catalysis, and provides feasible guidance for the design of low-cost and high-effect ORR catalysts.