Facile template-induced synthesis of Ag-modified TiO2 hollow octahedra with high photocatalytic activity

Abstract

Noble metal/titania hollow nanomaterials usually exhibit excellent photocatalytic activity because of their high specific surface area, low density, good surface permeability, strong light-harvesting capacity, and rapid interfacial charge transfer. However, the present preparation methods usually include complicated and multistep procedures, which can cause damage to the hollow nanostructures. In this paper, a facile template-induced synthesis, based on a template-directed deposition and in situ template-sacrificial dissolution, was employed to prepare Ag-modified TiO2 (Ag/TiO2) hollow octahedra using Ag2O octahedra as templates and TiF4 as the precursor. In the synthetic strategy, the shells of TiO2 hollow octahedra were formed by coating TiO2 nanoparticles on the surface of Ag2O templates based on the template-directed deposition. Simultaneously, the Ag2O templates can be in situ removed by dissolving the Ag2O octahedral template in HF solution produced via the hydrolysis reaction of TiF4 in the reaction system. In addition, Ag nanoparticles were deposited on the inside and outside surfaces of TiO2 shells by effectively using the photosensitive properties of Ag2O and Ag+ ions under light irradiation, along with the formation of TiO2 hollow octahedra. The Ag/TiO2 hollow octahedra exhibited high photocatalytic activity because of their (1) short diffusion distances between photogenerated electrons and holes because of the thin shells of Ag/TiO2 hollow octahedral, (2) deposition of Ag nanoparticles on the inside and outside surfaces of TiO2 shells, and (3) rapid interfacial charge transfer between TiO2 shells and Ag nanoparticles. This work may also provide new insights into preparing other Ag-modified and hollow nanostructured photocatalysts.