"Inertness to chemical environment and long-term photostability has made TiO2 an important material... in commercial products... from drugs to foods, cosmetics to catalysts, paints to pharmaceuticals, and sunscreens to solar cells in which TiO2 is used as a desiccant, brightener, or reactive mediator... The catalyst itself is unchanged during the process and no consumable chemicals are required. This results in... savings and simpler operation of... equipment..."