Defect-induced enhanced dissociative adsorption, optoelectronic properties and interfacial contact in Ce doped TiO2: Solar photocatalytic degradation of Rhodamine B

Abstract

High electrical resistance and poor reactivity of Ce doped TiO2 serve as a bottleneck for photocatalytic reactions. The current work focuses on addressing the challenges by consciously introducing defects on the surface of composite catalyst to enhance the interfacial contact between oxides of Ce and Ti through thermal treatment. This provide a quantitative change in surface species viz. Ti3+, Ti4+, Ce3+, and oxygen vacancies, which were studied using X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy. The effect was noticed in terms of change in electrical, dissociative adsorption, intimate contact between Ti and Ce and also in reduction properties of the catalyst. Consequently, a sharp increase in the concentration of reactive oxygen species (ROS) was observed, which is necessary for carrying out the degradation reactions. Tailoring the properties of Ce doped TiO2 by thermal treatment in an inert atmosphere at 900 °C resulted in an increase of rate constant by 40% under solar light as compared to the catalysts of the same composition but annealed at the different heating condition. To further understand electrical resistance, the formation of defects and work function of the catalysts, ultra violet photoelectron spectroscopy (UPS) measurement was carried out. Results prove that the combined effect of defects and lowering of work function promoted the charge transfer between Ti and Ce. These findings may provide a way to understand and develop simple, inexpensive, and assuring catalysts for oxygen reduction reaction.