High-Energy Electron-Beam-Induced Evolution of Secondary Phase and Enhanced Photocatalytic Activity in Monoclinic BiEuWO ₆ Nanoparticles

A hydrothermally synthesized monoclinic phase of BiEuWO ₆ photocatalyst nanoparticles was irradiated with variable doses of high-energy electron beam irradiation (EBI). Structural and morphological changes in unirradiated (referred to as control) and electron-beam-irradiated (referred to as EBI) nanoparticles were characterized by X-ray diffraction, Raman spectroscopy, and field emission scanning electron microscopy. At 50 kGy dose, evolution of a small fraction of a crystalline secondary orthorhombic phase along with a primary monoclinic phase is observed. This is further confirmed by X-ray diffraction as well as Raman spectroscopy. Single-phase and multiphase Rietveld refinements were carried out on the powder X-ray data of the control and EBI samples, and the phase fractions were deduced. Further diffused reflectance spectroscopy, steady-state fluorescence emission spectroscopy, and Brunauer-Emmett-Teller surface area were used to characterize the samples. A significant increase in the visible light photocatalytic activity is observed in the two-phase nanomaterials above an optimum dose of 50 kGy for the degradation of Congo red dye. The structural and morphological implications are investigated in detail to understand the enhancement in the photocatalytic activity of the EBI samples. This work demonstrates the potential of high-energy electron beam irradiation for development of superior crystalline semiconductor photocatalysts.