NiCo2O4 nanosheets as a novel oxygen-evolution-reaction cocatalyst in situ bonded on the g-C3N4 photocatalyst for excellent overall water splitting

Abstract

A 2D/2D coupled NiCo₂O₄/g-C₃N₄ nanostructure was fabricated through an in situ growth strategy. NiCo₂O₄ worked as a novel oxygen-evolution-reaction cocatalyst, and the intimate interface combination by surface bonding and the related cooperative effect between NiCo₂O₄ and g-C₃N₄ were comprehensively explored. Consequently, the separation and migration of photo-generated charge carriers for g-C₃N₄ were efficiently promoted, as well as the energy barriers of the oxygen evolution reaction were reduced. NiCo₂O₄/g-C₃N₄ showed obviously enhanced photocatalytic O₂-evolution activity (4.6 times that of bare g-C₃N₄), and the corresponding AQY achieved 4.9% at 380 nm. Then, Pt as a hydrogen-evolution-reaction cocatalyst was employed to cooperate with NiCo₂O₄ to construct dual cocatalyst loaded g-C₃N₄ for photocatalytic overall water splitting, in which H₂ and O₂ simultaneously evolved in a stoichiometric ratio of 2 : 1, and the AQY for H₂ evolution reached 2.8% at 380 nm. Consequently, this work demonstrates a reliable strategy for g-C₃N₄ to construct a photocatalytic system for efficient overall water splitting.