Sulphur, nitrogen-doped TiO₂/graphene oxide composites as a high performance photocatalyst

Abstract

Sulphur (S), nitrogen (N)-doped TiO2/graphene oxide (GO) composites were environmentally friendly synthesised using thiourea (CS(NH2)2) as a binary-element doping reagent by a simple colloidal blending method. The S, N-doped TiO2/GO composites show higher photocatalytic degradation rates on methyl orange (MO) compared to TiO2. The average value of k (the apparent rate constant) for the S, N-doped TiO2/5%GO (k = 0.035 min−1) was found to be eight times higher than that of TiO2 grown in solution (k = 0.0038 min−1) and four times higher than that of P25 (k = 0.008 min−1). The investigation showed that the contribution of GO to the high photocatalytic activities of the composites come from its high specific surface area, oxygen-containing functional groups and large aromatic domains that were inclined to be bound by conjugated MO molecules via π–π stacking. The doping of S and N can increase the numbers of photo-generated electrons and holes, which produce more charge carriers to form reactive species, and thus promote the degradation of MO. This work could offer a route to improve the photocatalytic activities of TiO2 and facilitate their application in reality.