Oxygen Vacancies Induced NiFe-Hydroxide as a Scalable, Efficient, and Stable Electrode for Alkaline Overall Water Splitting

The demand for non-noble bifunctional electrocatalysts for overall water splitting was increased for simplifying water-splitting systems and accelerating commercialization. Herein, oxygen vacancy-rich nanoporous nickel foam (NF) electrodes decorated with nanosized NiFe layered double hydroxide are fabricated by a facile and scalable electrochemical treatment using FeCl3 solutions as OER and HER electrocatalysts in an alkaline medium. The roles of Cl- and Fe3+ ions are analyzed by electrochemical and surface-enhanced X-ray analysis techniques. The Cl anions increase the active sites by producing nanopores on the NF surface and promote oxygen vacancies, while the Fe cations enhance the inherent catalytic activity for water oxidation. The FeCl3-treated NF shows enhanced catalytic activities and maintains an overpotential of 520 mV at 100 mA cm(-2) for 150 h in a 10 cm(2) single cell. The results demonstrate that the simple electrochemical treatment is a promising method to produce oxygen vacancy-induced scalable electrodes with large surface areas for various applications.