C-N/TiO2 photocatalysts : effect of co-doping on the catalytic performance under visible light

Aim of this work is the synthesis of titanium-based photocatalysts co-doped with both C and N, exhibiting improved photocatalytic activity under visible light irradiation. The preparation of the catalysts consists of a two step process: during the first one, the synthesis of the catalyst doped with nitrogen has been carried out, whereas in the second step carbon has been introduced in different amounts. The photocatalytic activity has been evaluated in the gas phase reaction of NOx abatement under visible light irradiation. The characterization has been carried out by N2 physisorption, TPO (temperature programmed oxidation), DRS (diffuse reflectance spectroscopy) and XPS (X-ray Photoelectron Spectroscopy) in order to investigate both structural and physico-chemical features of the samples and their correlation with the catalytic activity. An effective promotion effect of the dopants has been observed; in particular, the synergic co-presence of both N and C produced a significant narrowing of the TiO2 band gap with the consequent extension of the photocatalytic activity towards the visible part of the light spectrum.