One-pot topotactic synthesis of Ti3+ self-doped 3D TiO2 hollow nanoboxes with enhanced visible light response

Ti3+ self-doped anatase three-dimensional (3D) TiO2 hollow nanoboxes were synthesized via a topological transformation process involving template participation by a facile one-pot hydrothermal treatment with an ethanol solution of zinc powder and TiOF2. It is worth noting that the 3D TiO2 hollow nanoboxes are assembled from six single-crystal nanosheets and have dominant exposure of the {001} facets. It is found from EPR spectra that adding zinc powder is an environment-friendly and effective strategy to introduce Ti3+ and oxygen vacancy (O-v) into the bulk of 3D hollow nanoboxes rather than the surface, which is responsible for their enhanced visible photocatalytic properties. The photocatalytic activity was evaluated by measuring the formation rate of hydroxide free radicals using 7-hydroxycoumarin as a probe. The sample prepared with zinc/TiOF2 mass ratio of 0.25 exhibited the highest RhB photodegradation activity under visible-light irradiation with a degradation rate of 96%, which is 4.0-times higher than that of pure TiO2. The results suggest a novel approach to construct in-situ 3D hierarchical TiO2 hollow nanoboxes doped with Ti3+ and O-v without introducing any impurity elements for superior visible-light photocatalytic activity. (C) 2018, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.