2. Characteristics of the most widely used photocatalyst: titanium dioxide

At present, most applications use titanium dioxide as a semiconductor, and the spectral range concerned by photocatalysis can be considered to be mainly UV (λ < 384 nm) and a small part of the visible (380 to 400 nm) ( 3 ): anatase-structured titanium dioxide, the catalyst most widely used in photocatalysis, absorbs around 4% of solar photons. However, as we shall see in §6, current research is aimed at developing catalysts active at wavelengths above 400 nm, in order to utilize a greater number of photons in the visible range.