La0.5Sr0.5Fe0.5Ti0.5O3 as a Bifunctional Catalyst for H2/O2 Fuel Cells: Towards Enhanced Stability and Electroactivity

Abstract

To address the rising demand for H2 for fuel cells, hydrogen is produced through water splitting (electrochemically/photoelectrochemically).Although perovskite-structured materials show promise for the oxygen reduction reaction (ORR), their effectiveness in the oxygen evolution reaction (OER) poses a challenge. Consequently, there’s a growing demand for bifunctional catalysts exhibiting high electroactivity across a broad pH range. One potential candidate for exploration as a negative electrode in batteries and fuel cells is LaFeO3. With co-substitution of Sr and Ti, La0.5Sr0.5Fe0.5Ti0.5O3 (LSFT) is formed and explored as an air electrode. In this study, we systematically assess LSFT as a bifunctional catalyst across a broad pH spectrum of electrolytic solutions. LSFT displays increased current densities in both the OER and hydrogen evolution reaction (HER) domains, alongside improved stability, notably in neutral conditions. Our investigation incorporates Density Functional Theory (DFT) simulations to determine surface binding energies and construct a Pourbaix diagram. The results underscore the robustness of LSFT as a perovskite-based bifunctional catalyst, achieving a cycle stability exceeding 600 cycles and a chronopotentiometric stability of 1500 h with a stable potential of ∼2 V at the current density of 150 mA/cm2 in the neutral environment.