Ni-based heterostructure with protective phosphide layer to enhance the oxygen evolution reaction for the seawater electrolysis

The seawater electrolysis to generate hydrogen is a promising method to supply clean energy because the hydrogen has a high energy density and near zero carbon emissions. However, the competitive chlorine evolution reaction (ClER) and chloride-induced corrosion have a significant negative effect for the oxygen evolution reaction (OER), which leads to low current density and poor catalytic stability of the seawater electrolysis. Here, a heterostructure of NiO/Ni3S2 coated by protective Ni5P4 layer is designed as an OER electrocatalyst (NiO/Ni3S2@Ni5P4) for seawater electrolysis. Because of the enhanced capacity of electron transfer, accelerated reaction kinetics, and increased exposed active sites, the resulting electrocatalyst achieves the OER overpotential of 280 and 310 mV at 10 mA cm−2 for the freshwater and seawater electrolysis, respectively. More importantly, the electrocatalyst presents excellent catalytic stability of OER over 100 h at 100 mA cm−2 with negligible decay due to its good corrosion resistance. This work offers new inspiration for the design of effective electrocatalysts for the seawater electrolysis.