Reactive magnetron sputtering based synthesis of WO3 nanoparticles and their use for the photocatalytic degradation of dyes

Current study explores the synthesis of WO3 nanoparticles using highly effective novel physical vapour deposition process, reactive magnetron sputtering technique followed by annealing at different temperatures. The characterization of the synthesized samples were carried out by powder XRD, Raman spectroscopy, FE-SEM, TEM, BET, and diffuse reflectance spectroscopy (DRS) to check the crystallinity, morphology, surface area, and optical properties, respectively. Results display that the crystallinity and the crystallite size increases after heating the samples continuously. The morphology was found to be spherical type with high aggregation at low temperature. As-deposited nanoparticles display the highest surface area 66.78 m(2)/g and it decreases up to 20.45 m(2)/g with increasing the particle size up to 48 nm. The photocatalytic activity of the WO3 nanoparticles was evaluated in the degradation reactions of rhodamine B (Rh B), indigo carmine (IC), and Congo red (CR) in aqueous solution under UV-vis radiation. The highest photocatalytic activity was observed with highly crystalline WO3 nanoparticles and the order of the different organic dyes degradations was: IC > Rh B > CR. The degree of mineralization of organic dyes by WO3 nanoparticles was determined by total organic carbon (TOC) analysis and reaching percentages of mineralization of 76% Rh B, 87% for IC, and 8% for CR for 96 h of lamp irradiation. A proposed mechanism for the photocatalytic activity of synthesized WO3 was investigated in the presence of different scavengers which suggested that mechanism occurs through hydroxyl radicals rather than holes and peroxide radicals.