Fe₂O₃/NiO Interface for the Electrochemical Oxygen Evolution in Seawater and Domestic Sewage

Hydrogen production from the electrolysis of seawater and domestic sewage is more attractive than that from pure water, especially in regions where freshwater resources are scarce. However, under such harsh conditions, higher requirements are put forward for the catalytic activity and adaptability of a catalytic electrode. Herein, we advance an ultrasimple dipping-and-heating method to engineer the surface of Ni foam (NF) into an interface-rich FeNi oxide layer and realize an exceptional oxygen evolution reaction (OER) performance. It only requires overpotentials of 182 and 267 mV to achieve current densities of 10 and 1000 mA cm^-2 in 1 M KOH, respectively, which are significantly lower than those of the recently reported catalysts. The as-prepared FNE300||MoNi₄/MoO₂ electrolyzer realizes the industrial demand of 500 mA cm^-2 at low voltages of ∼1.75 V for overall alkaline natural seawater and domestic sewage electrolysis, as well as satisfactory stability. Density functional theory (DFT) calculations indicate that modifying the electronic structure so as to optimize the intermediate adsorption is well achieved by constructing the interfaces between NiO and Fe₂O₃. The interaction of Fe with oxygen intermediates can be optimized by e^--e^- repulsion between Ni²⁺ and oxygen intermediates. This work provides a facile approach to fabricate an electrocatalyst for seawater and domestic sewage electrolysis, which is of great significance to the synergetic development of hydrogen economy and environmental science.