Tuning the Photocatalytic Performance of Degussa P25 through Phase Ratio Optimization

Development of sustainable energy sources and methods for proper waste management is the need of the hour. Photocatalysis could be one of the potential solutions to mitigate both these problems. But, certain issues like narrow absorption range, low surface area and high charge carrier recombination limit the photocatalytic performance of catalysts like Degussa P25 (TiO2 powder). In this study, the effect of phase ratio on the physicochemical properties of Degussa P25 (DP25), particularly the dependence of photocatalytic activity on phase ratio is studied. The phase ratio of DP25 has been tuned to have different percentages of anatase and rutile phases via calcination. X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), UV-vis spectroscopy and Photoluminescence (PL) were used to determine the structural, morphological and optical properties of the samples. XRD analyses confirmed that all the samples are in mixed phase with nanoscale crystallite sizes are found to be in the nanoscale. The phase ratio of anatase to rutile content of the samples was calculated using Spurr's formula. The anatase to rutile (A/R) phase ratio was found to decrease with increase in calcination temperature. Tauc's plot was used to determine the optical band gaps of the samples. PL studies were used to identify the trap levels. Photocatalytic test of the samples were conducted under Ultra Violet (UV) irradiation using Methylene Blue (MB) as probe pollutant. The role of phase ratio on photocatalytic performance was analyzed. The sample with A/R ratio 1.44 showed superior photocatalytic activity compared to others. This study confirms the need of phase ratio optimization of Degussa P25 to improve its photocatalytic performance further.