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 mol% 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 electron trapping by partially filled 4f orbitals of Ho3+ ions, change in NPs morphology and the red shift of the optical band gap resulted the best photocatalytic performance of Zn0.97Ho0.03O NPs. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

Nanocrystalline ZnO nanoparticles were synthesized through a modified sol-gel method, and the enhanced photocatalytic activity of Zn1-xHoxO (x = 0.01, 0.03, and 0.05) NPs was investigated. The structural properties and morphological evolution were characterized using X-ray diffraction and field emission scanning electron microscope. The doping led to a red shift in the optical band gap and decreased electron-hole recombination rate, resulting in improved photocatalytic performance.