Highly durable FeNiSx/NiFe(OH)x electrocatalyst for selective oxygen evolution reaction in alkaline simulated seawater at high current densities

In this study, in-situ growing of FeNiS/NiFe(OH) on nickel form (NF) is successfully realized using a facile corrosion engineering process followed by a fast and mild sulfurization process, and applied as the anode for seawater electrolysis. The obtained anode requires only a low overpotential of 270 mV at a high current density of 100 mA cm in alkaline simulated seawater and maintains mechanical stability at an industrial-level current density of 1 A cm without corrosion. DFT calculations reveals that the FeNiS/NiFe(OH) has high selectivity towards oxygen evolution reaction (OER) against chlorine evolution reaction (ClER). For overall seawater electrolysis using it as the bifunctional electrocatalyst, the electrolyzer only requires a low cell voltage of 1.60 V at 10 mA cm and can sustain stable at the industrial-level current density of 1 A/cm with a cell voltage of 2.81 V, achieving a high hydrogen productivity without the catalyst deterioration.