Zinc oxide-based materials with enhanced sunlight-driven photo- and photo-electro-catalytic activity

Abstract

Current trend in photocatalysis is to develop efficient semiconductors which can be activated by absorbing sunlight. Which wavelength of sunlight will be absorbed depends on the semiconductor band gap; semiconductors with a wide band gap (> 3 eV) can absorb only UV light (5% of sunlight), while those with a narrow band gap (< 3 eV) can be activated by visible light (45% of sunlight). Zinc oxide (ZnO) is promising semiconductor with band gap of 3.37 eV. Various approaches have been applied to modify its optical properties, for example: incorporation of different metal and nonmetal ions or defects into the crystal structure, particles’ surface sensitization or hydrogenation. In this study, we examined the influence of different defects present in ZnO particles on their photo- and photo-electro-catalytic properties. Processing of ZnO particles were carried out in order to introduce: (1) lattice defects, through microwave procedure, (2) surface defects, through mechanical activation, and (3) surface defects, trough composite with polyethylene oxide. Synthesized particles were characterized by XRD, FESEM, laser diffraction particle size analyzer, Raman, UV-Vis diffuse reflectance and photoluminescence spectroscopy. The results of achieved photo- and photo-electro-catalytic tests indicate that both, structural and surface, defects enhanced sunlight-driven activity of ZnO particles.