CoO Promoted the Catalytic Activity of Nitrogen-Doped MoS₂ Supported on Carbon Fibers for Overall Water Splitting

Non-noble metal electrocatalysts have recently witnessed increasing attention for the hydrogen evolution reaction (HER) in acidic electrolytes. However, in alkaline electrolytes, the slow kinetics of water splitting leads to poor HER activities. In this study, we describe the preparation of a hybrid material consisting of cobalt oxide (CoO) decorated on nitrogen-doped MoS2 supported on carbon fibers (CoO/N–MoS2/CF) through a two-step process combining hydrothermal technique and electrochemical deposition. The electrochemical properties of the CoO/N–MoS2/CF electrocatalyst were assessed in alkaline medium. The results revealed that CoO/N–MoS2/CF exhibits excellent bifunctional electrocatalytic activity for the HER and oxygen evolution reaction (OER). The CoO/N–MoS2/CF delivered a current density of 10 mA/cm2 at an overpotential of only 78 mV for the HER and a current density of 50 mA/cm2 at 458 mV for the OER in 1.0 M KOH, performing better than many noble metal-free electrocatalysts. The enhanced catalytic properties of the hybrid nanomaterial could be ascribed to its hierarchical structure, and increased number of active sites, as well as the synergetic cooperation between its different components. Additionally, the CoO/N–MoS2/CF nanomaterial was investigated as both cathode and anode for full water splitting in 1.0 M KOH. The water electrolyzer delivered a maximum current density of 53 mA cm–2 at an applied cell voltage of 1.5 V, which is very favorable for overall water-splitting applications.