We designed and fabricated novel TiO₂-based visible-light-sensitive photocatalysts, in which Fe（III）or Cu（II）species were grafted on a TiO₂ surface. These showed high photocatalytic activity under indoor light conditions, demonstrating air-cleaning, antiviral, and self-cleaning effects. Recently, we evaluated the antibacterial and antiviral activities of these materials in an airport terminal and hospital, where the risks of infection are high, and confirmed that the novel visible-light-sensitive photocatalysts are effective against bacteria in actual indoor environments.

This review article mainly focuses on the development of high-sensitive photocatalyst materials which are results of “project to create photocatalyst industry for recycling-oriented society” organized by New Energy and Industrial Technology Development Organization (NEDO). Three new photocatalyst materials were proposed. Decahedral TiO₂ is the highest photocatalytic activity under UV irradiated. WO₃ modified copper compounds are able to decompose VOC under visible light irradiated. TiO₂ modified copper compounds have very strong antibacterial and antivirus effects. We are developing new products which are applied those new photocatalyst materials.

Titanium dioxide photocatalysis is Japan-originated technology, and is applied to a variety of environmental materials. Photocatalysis has two main functions, decomposition by photo inductive effect and superhydrophilicity by photo inductive effect. The decomposition function decomposes all organic matter using oxidizing propertied of titanium dioxide. The superhydrophilicity function repels water on the surface of a material. This document describes the summary of photocatalytic air purification system, three main effects that are deodorization, decomposition of VOC (Volatile Organic Compounds), and anti-bacteria and anti-virus, and the future of photocatalytic air purification.