Promoting electrocatalytic water oxidation through tungsten-modulated oxygen vacancies on hierarchical FeNi-layered double hydroxide

With growing demand for renewable energy to protect the environment, it is urgent to develop prominent and robust catalysts toward oxygen evolution reaction (OER) through a facile procedure to reduce energy consumption. However, the limited intrinsic activity of anodic electrocatalysts hinders the wide application of water splitting electrolyzers. To promote the electronic property of the anodic electrodes, enhancing the concentration of oxygen vacancies in electrocatalysts could effectively modulate the intrinsic electronic states and significantly accelerate the charge transfer ability of the electrocatalysts. Herein, a series of hierarchical FeNiW-layered double hydroxide (FeNiW-LDH) in situ growth on Fe foam are prepared via W doping into FeNi-LDH by an electrochemical corrosion engineering strategy. Remarkably, by virtue of excellent electronic conductivity and two-dimensional lamellar configuration, the representative FeNiW-LDH exhibits outstanding electrochemical activity for water oxidation with a low overpotential (η₁₀ = 202 mV) and a small Tafel slope (55.7 mV dec^–1). FeNiW-LDH could also maintain stability for 120 h at 300 mA cm^–2. Moreover, FeNiW-LDH in situ growth on Fe foam with a larger area (16 × 23 cm²) could be successfully prepared under laboratory conditions, which could facilitate the laboratory-made catalyst moving toward industrialization. The doping W into FeNi-LDH could significantly enhance the concentration of oxygen vacancies, which was proved by electron paramagnetic spectroscopy. In addition, theoretical calculations also demonstrated the oxygen vacancies efficiently tune the intrinsic electronic structure of FeNi-LDH and optimize the intermediates adsorption energy, accelerating the OER reaction kinetics.