Rational Electronic Regulation and Surface Reconstruction in Fe‐Doped La _0.5 Ba _0.5 CoO _3–δ Perovskite for High‐Current‐Density Hydrogen Evolution Reaction and Efficient Oxygen Evolution Reaction

Abstract Perovskite oxides are gradually becoming promising catalysts for electrocatalytic water splitting, with rational electronic structure modulation enabling exceptional activity, stability, and cost‐effectiveness. Herein, Fe‐doped La 0.5 Ba 0.5 CoO 3–δ (LBC) perovskites are synthesized via a sol‐gel method, and the optimized composition, La 0.5 Ba 0.5 Co 0.6 Fe 0.4 O 3–δ (LBCF 0.4 ), exhibits dramatically increased hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activities. Notably, Fe doping effectively modulates the electronic structure, optimizes the adsorption energy of H * , and accelerates the reaction kinetics, endowing LBCF 0.4 with remarkable HER activity, particularly at high current densities. Furthermore, an in situ surface reconstruction during HER leads to the formation of an amorphous Co‐rich layer with exposed active sites. Concurrently, LBCF 0.4 demonstrates unprecedented stability, maintaining performance for over 2000 h at 500 mA cm −2 . For OER, LBCF 0.4 demonstrates a 42% lower overpotential than LBC (301 vs 473 mV @ 10 mA cm −2 ) and a 36‐fold higher turnover frequency at an overpotential of 300 mV. This significant performance improvement can be ascribed to Fe 4+ species, the increased content of oxygen vacancies, and the in situ formation of amorphous Co/Fe (oxy)hydroxides. This work highlights the importance of electronic regulation and structural evolution in electrocatalysis, offering a promising strategy for designing efficient perovskite catalysts.