Oxygen defect-rich In-doped ZnO nanostructure for enhanced visible light photocatalytic activity

Developing high-efficiency photocatalyst for the degradation of environmental pollutants under visible light is ideal. In this study, indium-doped zinc oxide with rich oxygen vacancy defects (In-OV-ZnO) was successfully fabricated by using a facile solution method followed by annealing process. The morphological, structural, and optical properties of the as-synthesized samples were studied. The X-ray diffraction measurements revealed the positions of the main peaks in the synthesized samples with In3+ ions and oxygen vacancies were slightly shifted. The analysis of SEM and TEM showed that the In-OV-ZnO samples were in the nanoscale regime (20-50 nm) with hexagonal crystalline morphology. The UV-vis DRS spectra showed that In-OV-ZnO samples had the band gap value of 3.14 eV. Based on photocurrent analysis and photoluminescence studies, the oxygen vacancy of In-OV-ZnO favored the electron-hole pairs' separation. Photocatalytic studies revealed that the In-OV-ZnO samples display better photocatalytic activities of methylene blue (MB) and methyl orange (MO) under visible light irradiation, which exhibited maximum degradations of 96.84% and 90.05%, respectively. The enhanced photocatalytic performance can be ascribed to the synergistic effect of the oxygen vacancy defects and the In3+ ions favoring efficient electron-hole separation, which provided several active sites. This work develops a study to enable an efficient and cost-effective design of novel photocatalysts and offers insight into the influence of surface defects in enhancing photocatalytic activity.