Ripple-like NiFeCo sulfides on nickel foam derived from in-situ sulfurization of precursor oxides as efficient anodes for water oxidation

Mixed first-row transition metal-based sulfides with specific nanostructure hold the promising performances for oxygen evolution reaction (OER). Herein, based on the optimum Ni/Fe/Co ratio (8/1/1) in electrolyte for electrodeposition on nickel foam (NiFeCo/NF), ripple-like sNiFeCo/NF has been prepared as efficient electrode for water oxidation through solvothermal sulfurization. The unique ripple-like structures contain many pores and voids with many wrinkles and distortions, which may enlarge the surface area and expose more active sites, improving the contacting of catalyst/electrolyte interfaces and facilitate electron transfer. sNiFeCo/NF shows better OER activity than NiFeCo/NF, requiring overpotential of 180 mV to deliver 100 mA cm−2 and a low Tafel slope of 50.4 mV dec−1. In order to further overcome the poor stability of sNiFeCo/NF, Fe hydroxide film has been electrodeposited on the surface of sNiFeCo/NF (sNiFeCo-Fe/NF), which leads to enhanced stability at the sacrifice of partial activity loss of sNiFeCo/NF. The electrodeposited Fe is supposed to protect NiFeCo-based sulfides from severe corrosion in alkaline and ensure the OER activity in long-term water oxidation. It implies a balance between activity and durability of NiFeCo sulfides. This work may provide a facile routine to fabricate ternary Ni-Fe-Co sulfides as efficient electrocatalyst for water oxidation.