Water Splitting Performance Enhancement of the TiO2 Nanorod Array Electrode with Ultrathin Black Phosphorus Nanosheets

Abstract Metal free two‐dimensional (2D) semiconductor nanomaterial black phosphorus (BP) is a promising photocatalyst for solar H 2 evolution. Here, ultrathin BP nanosheets were prepared through organic salt sodium citrate assisted exfoliation of bulk BP. Further, an efficient photoelectrode for photoelectrochemical water splitting was developed based on TiO 2 nanorod arrays, coated with ultrathin black phosphorus nanosheets. Compared to the pure TiO 2 nanorod arrays, this structure exhibits reduced photoluminescent emission, longer carrier lifetime, and a strong photocurrent density enhancement of about 140 %. The high photoelectrochemical performance indicated the formed 2D‐1D BP/TiO 2 heterostructure facilitates the charge separation and transfer. The interfacial interactions between black phosphorus and TiO 2 were thoroughly investigated with XPS and FTIR spectroscopy.