Enhanced separation efficiency of photo-induced charge pairs and sunlight-driven photocatalytic performance of TiO 2 prepared with the assistance of NH 4 Cl

The photocatalytic performance of TiO 2 is significantly limited by its high recombination rate of photo-generated charge carriers, and therefore it is essential to further boost the photocatalytic activity of TiO 2 . In this paper, to enhance the separation efficiency of the photo-generated charge carriers by surface state regulation, a series of TiO 2 photocatalysts were prepared by sol–gel method with the assistance of NH 4 Cl and studied by the Brunauer-Emmet Teller method, X-ray diffraction patterns, UV-VIS diffuse reflectance spectra, scanning electron microscopy with energy dispersive spectroscopy and surface photovoltage spectroscopy. The relative amount of •O 2 − was measured using nitrotetrazolium blue chloride (NBT) method. The photocatalytic activities of the samples under the simulated sunlight irradiation were investigated using Rhodamine B as the model dye. The results reveal that all the samples prepared with the assistance of NH 4 Cl display better photocatalytic activity than the reference TiO 2 and the enhancement mechanism was proposed. Graphical abstract