Doping level effect on sunlight-driven W,N-co-doped TiO2-anatase photo-catalysts for aromatic hydrocarbon partial oxidation

A series of nanosized W,N-co-doped anatase TiO2 catalysts with different dopant contents has been prepared by a microemulsion method and examined in the sunlight selective photo-oxidation of toluene and styrene. The activity results have been correlated with structural, electronic, and surface examinations of the catalysts done with the help of XRD–Rietveld, N2 physisorption and NH3 chemisorption–calorimetry, XPS, Infrared, and UV–visible spectroscopies. Irrespective of the reaction, a consistent reaction rate enhancement with respect to titania (nano-TiO2, P25) references and W-doped TiO2 systems is observed for single-phase anatase W,N-co-doped samples. This is likely linked with the decrease of the band gap energy decrease and results from a combined W–N cooperative effect on structural properties of the anatase network. W,N simultaneous presence also makes a drastic effect on selectivity, maximizing the yield to partial oxidation products. This appears related with surface properties of the materials.