Development of Cobalt Oxide-Decorated Reduced Graphene Oxide-Supported Nickel Alloy Coating for Efficient Photocatalytic Hydrogen Generation

Being a narrow band gap semiconductor, the photocatalytic activity of bare Ni2P is highly limited. However, a proper band gap tuning of Ni2P through effective composite formation furnishes a fruitful strategy for developing active photocatalytic materials. In this regard, the present work reports the application of an efficient photocatalytic ternary composite in the form of a coating formed from CoO/rGO and Ni2P. The simultaneous reduction of GO to rGO disperses crystalline CoO nanoparticles in it. The CoO-embedded rGO nanosheet can act as an efficient conducting material that helps to mediate the redox reactions in CoO and Ni2P. CoO/rGO enriches the catalytically active sites in the Ni2P surface with an improvement in the surface topography. Moreover, the possibilities of interactions such as hydrogen bonding among the oxygen functional groups in CoO/rGO, with phosphorus in Ni2P, lead to an intimate contact among them for the fast electronic movement for proton reduction. Consequently, the CoO/rGO-Ni2P composite coating displays a benchmark performance for solar-driven hydrogen generation and produces 4.98 mmol/g hydrogen for 1 h irradiation after a successful compositional tuning. The long-lasting activity and excellent stability of the composite coating, even after 15 cycles, are attributed to the additional role of Ni2P as a catalyst support bed for CoO/rGO which can impart stability to the entire catalyst system.