Significant enhancement in the photocatalytic activity of N, W co-doped TiO2 nanomaterials for promising environmental applications

In this work, a mesoporous N, W co-doped TiO2 photocatalyst was synthesized via a one-step solution combustion method, which utilized urea as the nitrogen source and sodium tungstate as the tungsten source. The photocatalytic activity of the N, W co-doped TiO2 photocatalyst was significantly enhanced by a facile UV pretreatment approach and was evaluated by measuring the rate of photodegradation of Rhodamine B under both UV and visible (lambda > 420) light. Following the UV pretreatment, the UV photocatalytic activity of the N, W co-doped TiO2 was doubled. In terms of visible light activity, the UV pretreatment resulted in an extraordinary >12 fold improvement. In order to gain insight into this substantial enhancement, the N, W co-doped TiO2 photocatalysts were studied using x-ray diffraction, transmission electron microscopy, N-2 physisorption, UV-vis absorbance spectroscopy and x-ray photoelectron spectroscopy prior to and following the UV pretreatment. Our experimental results have revealed that this significant augmentation of photocatalytic activity may be attributed to several synergetic factors, including increase of the specific surface area, reduction of the band gap energy and the removal of carbon impurities.