Hierarchical Amorphous\nCarbon-Coated Co/Co₉S₈ Nanoparticles on MoS₂ toward Synergetic\nElectrocatalytic Water Splitting

Abstract

The development of electrocatalysts with excellent performance,\naffordable price, and abundant reserves is an important way to realize\nthe overall water splitting. In this study, we design a unique preparation\nprocess to form a carbon-coated Co/Co₉S₈–MoS₂ bifunctional catalyst. Excessive H₂S generated\nin the decomposition process of ammonium thiomolybdate can partially\nsulfurize carbon-coated Co nanoparticles, and Co/Co₉S₈ mixed phases will be formed on MoS₂. The as-prepared\ncatalyst possesses good bifunctional electrocatalytic activity under\nthe alkaline environment for hydrogen evolution reaction (HER) and\noxygen evolution reaction (OER). The amorphous carbon-coated Co/Co₉S₈–MoS₂ composite shows a low\noverpotential of 128 mV for HER and 325 mV for OER in 1 M KOH solution,\nrespectively. Besides, the amorphous carbon shell can prevent Co/Co₉S₈ nanoparticles from corrosion, and the catalyst\nshows remarkable long-term cycle stability.