Coupled amorphous NiFeP/cystalline Ni3S2 nanosheets enables accelerated reaction kinetics for high current density seawater electrolysis

Rational designing efficient, low-cost and corrosion resistant electrocatalysts is a crucial priority for seawater electrolysis to give impetus to the development of hydrogen energy and carbon neutrality. Herein, an amorphous NiFeP/crystalline Ni3S2 (NiFeP/Ni3S2) heterojunction catalyst is legitimately constructed for seawater electrolysis. Such structure improves the conductivity of amorphous NiFeP and optimizes the electronic structure by keeping the metal active sites in a relatively high valence state. In situ/ex situ experimental and theoretical calculation results reveal that the amorphous/crystal heterostructure accelerates the reconstruction and reaction kinetics of catalysts, reducing the energy barrier for potential-determining step and leading to improved intrinsic activity. The constructed NiFeP/Ni3S2 shows the overpotential of 354 mV to drive current density of 800 mA cm−2 in the alkaline medium. Besides, under 100 mA cm−2, NiFeP/Ni3S2 can run stably for 600 hours in seawater electrolyte without any hypochlorite production, demonstrating its excellent chemical stability and corrosion resistance.