Photocatalytic water splitting from MXene and substoichiometric molybdenum oxide ultrathin nanowire Schottky heterojunction

Abstract

Due to the positive conduction band of MoO3, it is typically unable to generate hydrogen under photocatalysis. In this work, we reported direct photocatalytic hydrogen evolution from substoichiometric MoO3-x ultrathin nanowire using sacrificial triethanolamine. By incorporating trace amounts of oleylamine and the ligand polyvinyl pyrrolidone, blue ultrathin MoO3-x nanowires with the diameter of approximately 2 nm were effectively created through a simple hydrothermal method. These one-dimensional MoO3-x ultrathin nanowires boast a modified energy band structure, which promotes an elevated shift in the conduction band and favors the availability of more active sites. These factors jointly contribute to direct photocatalytic hydrogen evolution by MoO3-x ultrathin nanowires. Moreover, we introduced MXene Ti3C2Tx as a cocatalyst, enabling the fabrication of MXene Ti3C2Tx-MoO3-x composites via a simple two-phase composite method. The implementation of MXene Ti3C2Tx as a substrate effectively isolates photogenerated electron-hole duos, resulting in boosted performance in generating hydrogen and oxygen through photocatalysis. The optimized MXene Ti3C2Tx-MoO3-x composites demonstrate exceptional photocatalytic performance, with hydrogen and oxygen evolution rates reaching 36.1 and 1044.2 μmol·h-1g-1, respectively. These values signify a remarkable 6 and 3.2-fold increase over raw material. This method of synthesizing size-tunable MoO3-x nanowires and MXene Ti3C2Tx-MoO3-x composites presents a promising avenue for research in energy and allied fields.