Operando Reconstruction toward Dual‐Cation‐Defects Co‐Containing NiFe Oxyhydroxide for Ultralow Energy Consumption Industrial Water Splitting Electrolyzer

Abstract Nickel–iron oxygen evolution catalysts have been under the spotlight as substitutes for precious metals, however, they rarely operate efficiently in practical industrial electrolyzers due to their moderate activity. Guided by density functional theory, the interaction of cation vacancies and dopants can manipulate d band centers, thus gaining near‐optimal binding energies of the oxygenated intermediates and ultralow potentials. This principle is implemented experimentally by catalysis operando variations synthesis, more specifically, in situ Mo leaching from high‐entropy Co, Mo co‐doped NiFe hydroxide precursors form Co dopant and cation vacancy coexistent NiFe oxyhydroxide. Operando electrochemical spectroscopy uncovers that dual‐cation‐defects promote the readier oxidation transition of metal sites, thus contributing to a low overpotential of 255 mV at 100 mA cm −2 . Furthermore, dual‐regulated NiFe oxyhydroxide electrodes operate stably at 8 A in practical industrial electrolyzers with ultralow energy consumption of ≈4.6 kWh m −3 H 2 , verifying the feasibility of lab‐constructed novel catalysts towards industrialization.