Effect Of Reaction Time On The Phase Transformation And Photocatalytic Activity Under Solar Irradiation Of Tungsten Oxide Nanocuboids Prepared Via Facile Hydrothermal Method

Monoclinic WO3 nanocuboids were synthesized via a one-pot hydrothermal method in a highly acidic environment at 180 degrees C for different reaction times (12, 24, and 48 h). The phase transformation from orthorhombic to monoclinic and then to oxygen-deficient Magneli phase and an increase in optical bandgap from 2.43 to 2.70 eV were observed when the reaction time increased from 12 to 24 h and then to 48 h. All samples showed photocatalytic activity towards the degradation of methylene blue (MB) under solar light irradiation, which was strongly enhanced in the presence of hydrogen peroxide (H2O2). Sample prepared for 24 h showed the highest MB removal efficiency of 31.4% in the absence of H2O2, which was enhanced to 76% and 92% when adding 0.2 and 0.5 mL of H2O2, respectively. These results give insights into the phase transformation and photocatalytic mechanism of WO3 nanocuboids prepared via the hydrothermal method.