Construction of N-doped TiO2/SnO2 heterostructured microspheres with dominant {001} facets for enhanced photocatalytic properties

Abstract

Nitrogen-doped (N-doped) TiO₂/SnO₂ heterostructured microspheres with exposed mirror-like plane {001} facets were successfully fabricated by a conventional hydrothermal method and easy impregnation treatment. The morphology, structure and photocatalytic properties of the N-doped TiO₂/SnO₂ heterostructure were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, and transient photocurrent response. Characterization results indicated that in situ formed SnO₂ nanoparticles were uniformly grafted onto N-TiO₂ microspheres of ca. 2.0 μm in size. The mirror-like {001} surface of these microspheres was covered by square-shaped crystalline facets ca. 0.6 μm long. The formation of a heterojunction between SnO₂ and N-TiO₂ microspheres enhanced the separation efficiency of photogenerated electron–hole pairs and the light-harvesting capability, which significantly improved the photocatalytic performance. Furthermore, N-doped TiO₂/SnO₂ heterostructured microspheres with highly reactive {001} facets were used as a stable photocatalyst for the highest photocatalytic activity for bisphenol A degradation under UV and visible light irradiation compared with pristine TiO₂ and N-TiO₂. This result can be attributed to the unique structure and synergistic effect of the dominant mirror-like plane {001} facets, N doping and heterostructured interface. This study provides new possibilities for the development of TiO₂ with a dominant {001} facet-based heterostructure for environmental purification.