Enhanced photocatalytic activity of Ho3+ doped ZnO NPs synthesized by modified sol-gel method: An experimental and theoretical investigation

All nanocrystalline ZnO nanoparticles (NPs) were synthesized via modified sol-gel method and origin of the enhanced photocatalytic activity of the Zn1-xHoxO (x=0.01, 0.03 and 0.05) NPs were investigated. Structural properties and morphological evolution were characterized using X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM), respectively. Ultraviolet visible (UV-Vis) spectroscopy showed red shift of optical band gap on doping with minimum band gap of 3.10 eV for Zn0.97Ho0.03O. Photoluminescence (PL) spectroscopy showed decrease in electron-hole recombination rate with increasing doping up to 3 mole percent doping. Photocatalytic activity was measured from degradation of rhodamine B (RhB) and reaction kinetics were analyzed. Theoretical study showed good agreement with experimental band gap results. Decreased electron-hole recombination rate with doping due to…