Enhanced photo-sensing activity of In-doped ZnO nanoparticles synthesized by wet chemical method

Zinc oxide(ZnO) and Indium(In) doped ZnO samples are prepared using a cost-effective wet chemical method by changing the In concentration (1, 3, and 5 %). The X-ray diffraction (XRD) studies confirmed that these samples have a hexagonal wurtzite structure of ZnO. Diffuse Reflectance Spectroscopy (DRS) analysis revealed that doping of In into ZnO decreases the energy bandgap from 3.27 (ZnO) to 3.24 eV (ZnO:In(3 and 5 %)). Photoluminescence studies showed near band emission (NBE) and defect level emission (DLE) peaks. The intensity of these emission peaks decreases with an increase in doping concentration, which delays the recombination of the electron-hole pair. The photosensing properties, such as responsivity (R), detectivity (D), and external quantum efficiency (EQE) of the 3% In doped ZnO sample is found to be 59.5 × 10⁻² AW⁻¹, 63.6 × 10⁹ Jones and 138 % respectively. The photocatalytic behavior of the samples was studied against Methylene blue (M.B.) under visible light irradiation. It is observed that the 3 % In-doped ZnO sample produced a higher degradation efficiency of 84 % after 75 min irradiation time. The rate constant was found to be 0.015, 0.018, 0.024, and 0.019 min⁻¹ for the undoped, 1, 3, and 5 % In-doped ZnO samples, respectively.