B-site substitution in A2BO4 Ruddlesden–Popper perovskites for enhanced OER and HER in alkaline medium

Abstract

In this work, we systematically investigated the optimization of water-splitting performance in A₂BO₄-type (214-type) Ruddlesden–Popper (R–P) perovskite catalysts via B-site substitution. PrSrCoO₄, previously identified as a highly active bifunctional electrocatalyst, was selected as the parent material. A series of B-site-substituted perovskites, including PrSrCo_0.6Fe_0.4O₄ (Fe0.4), PrSrCo_0.6Fe_0.2Ni_0.2O₄ (Ni0.2), PrSrCo_0.6Fe_0.3Ir_0.1O₄ (Ir0.1), and PrSrCo_0.6Fe_0.3Ru_0.1O₄ (Ru0.1), were successfully synthesized. Structural and magnetic characterization confirmed that all catalysts belong to the tetragonal I4/mmm space group and exhibit paramagnetic behavior at room temperature. Among the series, Ir0.1 exhibited the most remarkable bifunctional electrocatalytic performance, achieving low overpotentials of 277 mV for the oxygen evolution reaction (OER) and 279 mV for the hydrogen evolution reaction (HER) at 10 mA cm⁻². This enhanced catalytic activity is attributed to Ir-induced synergistic effects, including optimized surface oxygen species, a favorable shift in the d-band center, and an increased proportion of high-spin (HS) Co³⁺. Overall, our experimental results broaden the electrochemical application potential of 214-type R–P perovskites and provided an ideal platform for deeper mechanistic understanding and rational catalyst design.