A-SiteHigh-Entropy Strategy Activated Cobalt-BasedPerovskite Oxides for Hydrogen and Oxygen Evolution Reactions

Perovskite oxides have garnered extensive interest as prospective catalysts for massive-scale green hydrogen generation through water electrolysis. Nevertheless, their practical utilization has been long constrained by the inadequate bifunctional hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) efficiency. Herein, A-site high-entropy perovskite (LaSmPrBaSr)0.2CoO3 (LSmPBSC) is fabricated via a scalable glycine combustion process, producing a phase-pure material with no elemental phase segregation. The incorporation of low-valence Ba and Sr with large-radius into the low-entropy (LaSmPr)0.33CoO3 framework triggers lattice strain, generates numerous oxygen vacancies, and adjusts the electronic configuration of Co at catalytic sites, thereby enhancing intrinsic reactivity and structural durability. The LSmPBSC demonstrates superior bifunctional electrocatalytic performance in 1.0 M KOH, necessitating minimal overpotentials of 237 mV (HER) and 336 mV (OER) to reach current density of 10 mA cm-2, respectively. Meanwhile, it exhibits remarkable long-term stability for both HER and OER, showing negligible degradation over 500 h at 100 mA cm-2. The integrated two-electrode electrolyzer for total water splitting attains 10 mA cm-2 at 1.78 V exhibits outstanding operational longevity for 350 h. This A-site high-entropy approach offers a viable pathway for constructing perovskite oxide catalysts with improved water electrolysis efficiency.