Rare-Earth-Modified NiS₂ Improves OH Coverage for an Industrial Alkaline Water Electrolyzer

Abstract

The low coverage rate of anode OH adsorption under high current density conditions has become an important factor restricting the development of an industrial alkaline water electrolyzer (AWE). Here, we present our rare earth modification promotion strategy on using the rare earth oxygen-friendly interface to increase the OH coverage of the NiS 2 surface for efficient AWE anode catalysis. Density functional theory calculations predict that rare earths can enhance the coverage of surface OH, and the synthesis reaction mechanism is discussed in the synthesis process spectrum. Experimentally, by preparing a series of rare-earth-modified NiS 2, the relationship between OH coverage, active site density, and catalytic activity was established by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, time-resolved absorption spectra, and so on. The unique oxygenophilic properties of rare earths enhance OH coverage, thereby increasing the density of active sites for efficient catalysis. Furthermore, Eu 2 O 3 /NiS 2 was assembled into the AWE equipment and operated stably for over 240 h at a current density of 300 mA cm –2 under industrial conditions of 80 °C and 30% KOH. Rare-earth-modified NiS 2 exhibits better catalytic activity than traditional non-noble metal anode catalysts Ni(OH) 2 and NiS 2, providing a new approach for rare earth promotion to solve the problem of low OH coverage in the AWE anode.