Visible Light Activity and Photoelectrochemical Properties of Nitrogen-Doped TiO₂

Nitrogen-doped titania photocatalysts were prepared from titanium tetraisopropoxide or titanium tetrachloride and thiourea. The yellow powders obtained after calcination at 400−600 °C photocatalyze the mineralization of 4-chlorophenol by visible light (λ ≥ 455 nm). Different from previously published data these materials do not contain sulfur but instead nitrogen as the doping component inducing visible light photocatalysis. The measured band gap narrowing of 40−80 meV and the anodic shift of the quasi Fermi potential of 40−90 mV are in agreement with recent results on nitrogen-doped titania.