X-ray diffraction Rietveld structural analysis of Au–TiO2 powders synthesized by sol–gel route coupled to microwave and sonochemistry

Abstract

TiO2 is one of the most studied photocatalyst, however, in order to enhance the photocatalytic activity, several strategies for chemical or physical modifications have been reported. Among these strategies, microwave and sonochemistry assisted synthesis methods have been attracting attention due to the unique characteristics that can be achieved through it. Au–TiO2 nano powders were synthesized via microwave assisted sol–gel method (SG method) and sonochemistry assisted sol–gel method (SC method) with varying gold load, (containing 0.05, 0.1, 0.3, 0.7, 1.0, 3.0 and 5.0 wt% for SG method and 0.05, 0.1, 0.3, 0.7, 1.0 wt% for SC method). Subsequently, a calcination process was carried out at 450 °C for 3 h. Materials obtained were physicochemical analyzed by SEM, XPS, and XRD analysis. According to XRD analysis, the main crystalline phase of the materials was anatase. Average crystallite size and microstrain present in the powders were studied using the Williamson–Hall method and Debye–Scherrer equation. The crystal structure of all samples was refined by the Rietveld method, and a compression on the unit cell parameters was determined. These analyses revealed an increment in the unit cell strain when Au concentration was increased, and a decrease of the crystallinity in the powders when SG method was used. In the case of SC method samples, crystallinity and strain was found to remain constant.