Dopant-Dependent Surface Interaction Modulation by Pt with Hexagonal Perovskites for Robust Bifunctional Oxygen Electrocatalysts in Rechargeable Zn−Air Batteries

Abstract Rechargeable Zn−air batteries (ZABs) have attracted considerable attention as promising energy storage systems owing to their high theoretical energy density and environmental compatibility. However, their practical application is hindered by the sluggish ORR/OER kinetics at the air cathode. This study investigates low Pt-modified Fe- and Ni-doped hexagonal perovskites (BaTi0.8M0.2O3−δ, M = Fe and Ni) as robust bifunctional oxygen electrocatalysts, focusing on the modulation of their participating metal and electronic structures. Structural analysis confirms the formation of stable hexagonal phases, while Pt deposition induces distinct electronic reconstruction depending on the dopant species. With a higher ORR catalytic behavior than the Pt/BTO-Ni catalyst, the Pt/BTO-Fe catalyst demonstrates remarkable bifunctionality driven through dopant-dependent surface interaction modulation by Pt with optimized surface/lattice oxygen distribution. Notably, in full-cell ZAB tests, the optimized Pt/BTO-Fe catalyst achieved a comparable peak power density of 124.8 mW cm−2 with a remarkably low round-trip efficiency decay rate of 0.41%/h under stable operation for 60 h, compared to the commercial IrO2 + Pt/C benchmark (125.2 mW cm−2 and 1.39%/h) even at lower Pt content. These findings highlight the critical role of Pt2+-mediated interfacial interactions in governing catalytic durability, providing a rational strategy for designing highly durable bifunctional electrocatalysts for next-generation energy storage systems.