Harnessing Fe-and Co-based perovskites as trifunctional electrocatalysts

Abstract

The advancement of high-performance, economic, and earth-abundant electrocatalysts is essential for the development of sustainable energy systems, such as water-splitting devices, fuel cells, and metal-air batteries. In this context, the growing demand for multifunctional materials has driven the investigation of oxide-based perovskites with versatile electrocatalytic properties. Exploring perovskites, we report pristine Ba 2 FeCoO 6 (BFCO) and its mechanically activated form (S10-BFCO) as economic trifunctional electrocatalysts for oxygen evolution (OER), hydrogen evolution (HER), and the oxygen reduction reaction (ORR). Retaining a stable perovskite framework, S10-BFCO delivered an OER overpotential of 330 mV, an ORR onset potential of 0.785 V, and an HER onset of 230 mV (vs. RHE). Structural and surface stability under electrochemical conditions were confirmed through in-situ and ex situ characterizations. In-situ X-ray absorption spectroscopy (XAS), with and without applied potential, indicated that the cobalt oxidation state remains slightly above +2 in the electrolyte and is stable after withdrawal of potential. Postmortem analyses confirmed the coexistence of Co 2+ and Co 3+ oxidation states and the structural rigidity of BFCO. Exploiting the trifunctional activity, S10-BFCO was implemented as a cathode in zinc-air battery, delivering excellent bifunctional performance and long-term stability crossing 105 h of cycling. It highlights the potential of BFCO perovskite as a robust, rare-earth-free trifunctional catalyst for long-term, sustainable energy applications.