Environmental pollution and destruction on a global scale have drawn attention to the vital need for totally new environmentally friendly, clean chemical technologies and processes, the most important challenge facing chemical scientists in the field of green chemistry. Strong contenders as environmentally harmonious catalysts are photocatalysts that operate at room temperature and in a clean manner, while applications of such safe photocatalytic systems are urgently desired for the purification of polluted water, the decomposition of offensive atmospheric odors as well as toxins, the fixation of CO2 and the decomposition of NOx and chlorofluorocarbons on a huge global scale. To address such enormous tasks, photocatalytic systems that are able to operate effectively and efficiently not only under UV light but also under the most environmentally ideal energy source, sunlight, must be established. To this end, we are moving in a positive direction with various practical applications already at hand, as is described. The present report involves 1) new approaches in the design and development of second-generation titanium oxide photocatalysts which can operate effectively under visible light and/or solar beam irradiation, 2) practical industrial applications of titanium oxide photocatalysts in Japan, and 3) recent advances in green chemistry in Japan.
