TiO2 nanosheet/NiO nanorod hierarchical nanostructures: p–n heterojunctions towards efficient photocatalysis

Abstract

TiO2 nanosheet/NiO nanorod heterojunction hybrids have been developed through a hydrothermal route, where NiO nanorods (size: 5 nm in diameter and 20–40 nm in length) are deposited at the {0 0 1} facet of anatase TiO2 nanosheets. The photocatalysts were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), N2 adsorption-desorption analysis, UV–vis spectroscopy, X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy and time-resolved fluorescence. The TiO2/NiO photocatalysts exhibited good photocatalytic activities towards the degradation of methyl blue (MB) and phenol, and hydrogen generation efficiency under visible light irradiation. The maximum rate constant can be reached 0.0279 min−1 and 0.0135 min−1 respectively, which are about 12 and 10 times higher than that of TiO2 nanosheets. And the hydrogen generation efficiency is 10 times higher than physical mixing of TiO2 and NiO. Photocatalytic degradation efficiency remains more than 90% after 6 times cycle dye degradation, and the H2 production efficiency is almost the same after four cycles, suggesting good stability and reusability. The enhanced photocatalytic activities are associated with the rational design of TiO2/NiO hierarchical heterojunctions which ensues high photogenerated charge separation efficiency. With the improved photocatalytic performance, the TiO2/NiO heterojunction hybrids are expected to be potential photocatalysts in environmental and energy related areas.