Amorphous-microcrystalline heterostructured high-entropy oxysulfide/cerium oxide with strong electronic communication to boost water/simulated seawater splitting.

Exploring bifunctional transition metal-based oxysulfide with high activities, corrosion resistance and reaction selectivity is a promising strategy to realize efficient water/seawater splitting. Here, amorphous, high entropy and heterostructure strategies are coupled to construct the amorphous-microcrystalline heterostructured high-entropy oxysulfide/cerium oxide (a-NiCoFeOS/c-CeO) by one-step intermittent electrodeposition. With the strong interfacial electronic communication, a-NiCoFeOS/c-CeO shows high bifunctional activities with low overpotentials for hydrogen evolution reaction (47/63 mV) and oxygen evolution reaction (216/220 mV) at 10 mA cm in alkaline water/simulated seawater, respectively. The a-NiCoFeOS/c-CeO (+, -)-assembled electrolyzers require low cell voltages of 1.54/1.58 V to attain the current density of 10 mA cm for overall alkaline water/simulated seawater splitting. Moreover, a-NiCoFeOS/c-CeO exhibits strong activity retention and high Faradaic efficiency in alkaline water/simulated seawater. Significantly, a-NiCoFeOS/c-CeO (+, -) tolerates the industrial alkaline water splitting condition (500 mA cm in 6 M KOH @ 60 °C) with a strong durability of 210 h. Surface-reconstructed Ni/Co/Fe-based hydroxides/oxyhydroxides guarantee the high activity retention during the stability testing. The permiselective c-CeO and adsorbed sulfate enhance reaction selectivity and corrosion resistance by the inhibition of Cl approach. Herein, an innovative strategy is proposed for construction of efficient water/seawater electrocatalysts, showing great potential for industrial application.