First-principles study of the Pt@(Hf2-xZrx)B2O2 bifunctional ORR/OER catalysts

Abstract

Developing highly active and stable bifunctional catalysts for oxygen reduction (ORR) and evolution (OER) reactions is critical for advancing metal-air batteries. This work employs first-principles calculations to design Pt single-atom catalysts (SACs) anchored on solid-solution Hf_2-xZr_xB₂O₂ MBenes (Pt@Hf_2-xZr_xB₂O₂ ). Compositional tuning via Zr doping optimizes the electronic structure, modulating the work function and Pt d-band center. The catalyst with x = 0.625 (hexagonal Pt@Hf_1.375Zr_0.625B₂O₂) delivers exceptional bifunctional performance (η^bi = 0.96 V), with a lower OER overpotential (0.42 V) than IrO₂ (0.57 V) and a comparable ORR overpotential (0.54 V) to Pt (0.45 V). Mechanistic studies attribute this enhancement to optimized adsorption of oxygen intermediates (*O, *OH, *OOH) governed by the d-band center, alongside efficient charge transfer facilitated by Pt-O bonding. This work establishes solid solution engineering as a potent strategy for tuning SACs on MBene substrates, providing a foundation for next-generation bifunctional electrocatalysts.