Controlled synthesis of photoactive gallium based sillenite single crystal and its application in environmental remediation

Among the numerous photocatalytic materials studied for potential application in degradation of organic effluents and antibiotic wastes, sillenite materials emerge as important candidates. In the present work, Ga based sillenite has been used to degrade aqueous persistent organic pollutants such as bisphenol (BPA) and Norfloxacin (NF) in presence of natural solar irradiation. Sillenite based oxides have exhibited various physico chemical applications due to their photocatalytic nature. Here, gallium based sillenite, Bi24Ga2O39, has been successfully synthesized through two different techniques, hydrothermal route (HY) and solid state reaction (SS) method. X-Ray Diffraction patterns and Rietveld refinement of same revealed the occurrence of sillenite single phase. Morphological investigation by Scanning Electron Microscopy revealed regular tetrahedral morphology of HY sample. X-ray photoelectron and Raman spectroscopy were performed to analyze the chemical composition and its environment. UV–Visible spectroscopy on sillenites was used to analyze and calculate the effective optical band gap energy ~2.55 eV (HY) and ~2.76 eV (SS) respectively. Photoelectrochemical measurements performed on the samples showed appreciable photocurrent response (~1.9 μA/cm2 for HY sample). The photoactivity of samples have been utilized for degradation of aqueous persistent organic pollutants, such as methylene blue, norfloxacin and bisphenol A in presence of visible light degrading upto 92%, 82% and 84% (HY) respectively.