Controlling surface oxygen vacancies in Fe-doped TiO2 anatase nanoparticles for superior photocatalytic activities

Abstract

Introduction of defect structures into Fe-doped TiO2 nanoparticles (Fe@TiO2 NPs) has been shown to endow NPs with improved photocatalytic properties. However, current strategies for the preparation of defect-containing NPs require high temperature or complicated treatments, which can induce unwanted phase transition. In this paper, we report a facile method to introduce surface oxygen vacancies into anatase-type Fe@TiO2 NPs without altering the crystalline phase via simple pH treatments at moderate temperatures. Furthermore, we present the effects of pH on the formation of surface oxygen vacancies. The optimized treatment under basic conditions is revealed to promote the formation of oxygen vacancies on the surface of anatase Fe@TiO2 NPs and effectively reduces the particle size by more than 25%, thereby causing a significant enhancement in the photocatalytic activities of the NPs (e.g. ~3.5 times better in photocatalytic degradation rate of 4-CP as compared to acid-treated Fe@TiO2). Comprehensive structural and chemical characterizations reveal that the point defects are predominantly formed on the surface of anatase NPs, and their population can be maximized by use of basic pH conditions. Our results pave a way toward the facile and efficient engineering of surface defect structures on catalytic metal oxide NPs for the design of high-performance photocatalysts.