Manipulating the Electron Redistribution of Fe3O4 for Anion Exchange Membrane Based Alkaline Seawater Electrolysis

Seawater electrolysis is a green and sustainable method of producing clean hydrogen. However, the presence of chloride anion (Cl-, ~0.5 M) usually leads to competitive chloride oxidation reaction (ClOR). In this paper, the redistribution of electrons in Fe3O4 was manipulated using a fast melting salt combined with gas phase phosphating strategy. The Co/P dual-doped bifunctional catalyst (Co/P-Fe3O4@IF) was constructed on iron foam, which own excellent resistance to the adsorption of chloride ions by experimental and theoretical calculations. In addition, phosphating promotes the conversion of Fe2O3 to inverse spinel Fe3O4 phase, accelerating the dissociation of H2O. At the same time, Co doping manipulates the electron distribution and regulates the d-band center in Fe3O4, which is conducive to optimizing the ΔGH* and promoting the reconstruction process of OER, thus improving the catalytic activity in seawater. In alkaline seawater AEM electrolyzer, the catalyst can achieve a current density of 500 mA cm-2 at a voltage of 1.83 V without ClOR, and only 4.38 KWh can be consumed to produce hydrogen per cubic meter. This work opens up the possibility that transition metal oxides can become an important catalyst for hydrogen production from seawater.