Synthesis of spherical TiO2 particles with disordered rutile surface for photocatalytic hydrogen production

Abstract

One of the most important issues in photocatalysis research has been the development of TiO2-based photocatalysts that work efficiently under visible light conditions. Here, we report the monodispersed, spherical TiO2 particles with disordered rutile surface for use as visible-light photocatalysts. The spherical TiO2 particles with disordered surface were synthesized by sol-gel synthesis, followed by sequential calcination, and chemical reduction process using Li/Ethylenediamine (Li/EDA) solution. Variation of the calcination temperature allowed the crystalline properties of the calcined TiO2 samples, such as the ratio of anatase and rutile, to be finely controlled. The content ratios of anatase phase to rutile phase leads to different degrees of disorder of the rutile surface, which is closely related to the photocatalysis activity. Chemical reduction using the Li/EDA solution enables selective reduction of the rutile surface of the calcined TiO2, resulting in enhanced light absorption. As a result, we were able to synthesize spherical TiO2 photocatalysts having a disordered rutile surface in a mixed crystalline phase, which is beneficial during photocatalysis in terms of light absorption and charge separation. When used as photocatalysts for hydrogen production under solar light conditions, the chemically-reduced TiO2 particles with both the disordered rutile surface and mixed crystalline phase showed significantly enhanced catalytic activity.