TiO₂ Photocatalysis: A Historical Overview and Future Prospects

TLDR

TiO₂ is the dominant, inexpensive, and historically safe photocatalyst, known for efficient photoactivity, high stability, and dual UV‑induced redox and hydrophilic reactions that enable diverse industrial and building‑material applications. This review surveys the scientific progress and industrial uses of TiO₂ photocatalysis and outlines future prospects based on the authors’ work. The authors compile and analyze existing research and their own studies to assess TiO₂’s performance and potential developments.

Abstract

Photocatalysis has recently become a common word and various products using photocatalytic functions have been commercialized. Among many candidates for photocatalysts, TiO 2 is almost the only material suitable for industrial use at present and also probably in the future. This is because TiO 2 has the most efficient photoactivity, the highest stability and the lowest cost. More significantly, it has been used as a white pigment from ancient times, and thus, its safety to humans and the environment is guaranteed by history. There are two types of photochemical reaction proceeding on a TiO 2 surface when irradiated with ultraviolet light. One includes the photo-induced redox reactions of adsorbed substances, and the other is the photo-induced hydrophilic conversion of TiO 2 itself. The former type has been known since the early part of the 20th century, but the latter was found only at the end of the century. The combination of these two functions has opened up various novel applications of TiO 2 , particularly in the field of building materials. Here, we review the progress of the scientific research on TiO 2 photocatalysis as well as its industrial applications, and describe future prospects of this field mainly based on the present authors' work.