Manipulating interfacial charge redistribution in Mott-Schottky electrocatalyst for high-performance water/seawater splitting

Interface engineering is an effective approach towards developing low-cost highly efficient electrocatalysts for green hydrogen production in alkaline water or seawater environments. Herein, we have successfully fabricated an interface engineered Mott-Schottky heterostructure catalyst i.e., Fe3O4@Ni3S2, in which, Ni3S2 nanosheets are evenly dispersed on the surface of Fe3O4 flower-like nanosheets, which are supported by a Ni foam substrate. Due to the synergistic effect between Ni3S2 and Fe3O4, the Fe3O4@Ni3S2 heterostructure catalyst demonstrates remarkable catalytic activity under alkaline conditions which is attributed to the- highly exposed active sites, adjustment of the d-band center, and the built-in electric field at the interface. The catalyst Fe3O4@Ni3S2 has low overpotentials of 207 and 217 mV for the OER (oxygen evolution reaction) and 99 and 118 mV for the HER (hydrogen evolution reaction) in alkaline and seawater electrolytes, respectively, allowing it to yield a current density of 10 mA cm- 2 . Furthermore, the Fe3O4@Ni3S2||Fe3O4@Ni3S2 electrolyzer can achieve a current density of 10 mA cm- 2 for alkaline fresh water and seawater (1 M KOH + seawater) electrolysis at low voltages of 1.57 V and 1.58 V, respectively. This study presents a novel approach for fabricating high-performance multi-interface 3D catalysts for overall water/seawater splitting.