A Review on Metal‐Doped Zinc Oxide–Based Single and Multiple Phase Mixed Oxide Nanomaterials for Photocatalytic Applications
Teketel Girma Gindose, Enyew Amare Zereffa, Tsegaye Belege Atisme, Taju Sani, Tessema Derbe Hailegebreal
Abstract
This review focuses on the modification of ZnO for photodegradation of organic pollutants. ZnO is a versatile material which has great potential for photocatalytic remediation of organic pollutants. Nevertheless, it has a wide band gap energy and a high electron‐hole recombination. This leads to a low degradation efficiency for ZnO from the expected scale. Based on these limitations, significant techniques have been reported to modify the photocatalytic efficiency of ZnO nanoparticles. These are forming heterojunctions by doping, coupling, and compositing ZnO with other materials to improve its photocatalytic properties. The review also revised the phase analysis, particle size, morphology, elemental composition, functional group, and band gap energy of ZnO and its composites using XRD, TEM, SEM, EDS, =and UV‐vis, respectively. Furthermore, the review presented the synthesis methods of single‐metal doped, metal‐metal co‐doped, and multiphase ZnO‐based metal oxides. After the characterization was reviewed, the photodegradation efficiencies of ZnO and its composites were also reviewed. In most cases, the photocatalytic activity of ZnO photocatalyst is improved in its heterostructure form. However, the quaternary nanocomposite showed superior enhancement over other composites. In a nutshell, the integration of ZnO with metals, metal oxides, or other nanoparticles enhances the photocatalytic performance for wastewater treatment.