Construction of N-doped TiO₂/SnO₂heterostructured microspheres with dominant {001} facets for enhanced photocatalytic properties

Abstract

Nitrogen-doped (N-doped) TiO 2 /SnO 2 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 TiO 2 /SnO 2 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 SnO 2 nanoparticles were uniformly grafted onto N-TiO 2 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 SnO 2 and N-TiO 2 microspheres enhanced the separation efficiency of photogenerated electron-hole pairs and the light-harvesting capability, which significantly improved the photocatalytic performance. Furthermore, N-doped TiO 2 /SnO 2 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 TiO 2 and N-TiO 2 . 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 TiO 2 with a dominant {001} facet-based heterostructure for environmental purification.

Concurrent role of metal (Sn, Zn) and N species in enhancing the photocatalytic activity of TiO2 under solar light

“…A viable strategy to improve the photocatalytic activity of N-doped TiO 2 is the development of mixed oxide structures and heterojunctions able to limit recombination phenomena by enhancing the charge separation [3,4]. Due to their band structure, SnO 2 and ZnO have been frequently adopted to develop SnO 2 /TiO 2 and ZnO/TiO 2 heterojunctions [5][6][7][8][9][10][11][12], although reports of the formation of heterojunctions with N-doped TiO 2 have been much more scarce.…”

Highly Porous SnO2/TiO2 Heterojunction Thin-Film Photocatalyst Using Gas-Flow Thermal Evaporation and Atomic Layer Deposition

“…On the contrary, the SnO 2 /TiO 2 heterojunction gives rise to charge separation due to the potential difference, hence increasing the lifetime of the charge carrier and improving the interfacial charge transfer to the adsorbed surface. The photogenerated electrons and holes of the SnO 2 /TiO 2 heterojunction produced strong oxidizing radicals of •O 2 − and •OH from the water or oxygen on the surface of SnO 2 and TiO 2 , respectively, thereby degrading the organic pollutant (Figure 8) [31,32]. Since the •OH radical generated in the valence band of TiO 2 is a stronger oxidant, the introduction of the TiO 2 layer can improve the photocatalytic efficiency.…”

Cosputtered SnO2–ZnO composite nanofilms with improved dual function

“…[1][2][3][4][5][6][7][8] Several types of band alignment in composite systems are beneficial for photo-induced charge separation and improvements in their photoactive performances. [9][10][11][12][13][14] Among them, the type-II band alignment is useful for construction of wide-band-gap oxide composites for improved photoactivities. Furthermore, the recent progress on oxide heterostructures demonstrates that integration of two oxides with a suitable band alignment between the constituent compounds is a promising approach to improve the intrinsic properties of the semiconductor oxides for technological applications.…”

“…There are several chemical and physical routes for synthesis of SnO 2 and ZnO with various dimensions 1–8 . Several types of band alignment in composite systems are beneficial for photo‐induced charge separation and improvements in their photoactive performances 9–14 . Among them, the type‐II band alignment is useful for construction of wide‐band‐gap oxide composites for improved photoactivities.…”