Sun irradiated high efficient photocatalyst ZnO nanoparticles obtained by assisted microwave irradiation

Abstract

In this research microwave assisted zinc oxide synthesis applied to methylene blue dye mineralization is reported. This technique strongly influences the presence of certain intrinsic defects that is similar to those obtained by techniques where a rich oxygen atmosphere is used. These defects play a strong role in photocatalysis, showing a short time (70 min) at 95.3 % efficiency in methylene blue degradation under direct sunlight irradiation. Through X-ray diffraction, crystallinity, and nanoparticle size (5 nm) were obtained, meanwhile the morphology and elemental composition was observed by Scanning Electron Microscopy and Energy-Dispersive X-ray respectively. Additionally, Ultraviolet–Visible and Photoluminescence methods complete the analysis letting calculate the band gap (3.5 eV) and the presence/contribution of intrinsic defects. Such defects are identified as direct and strong contributors to carrier’s concentration separation and alternatively provoking low recombination levels, which is a characteristic desired in organic materials mineralization.