Metal oxides nanoparticles via sol–gel method: a review on synthesis, characterization and applications

Metal oxide nanoparticles (MONPs) have enormous applications such as in optical devices, purification systems, biomedical systems, photocatalysis, photovoltaics etc. In this review, we have explored a stable and efficient synthesis protocol of particularly four MONPs: titanium dioxide (TiO2), tin oxide (SnO2), tungsten oxide (WO3) and zinc oxide (ZnO) for getting desired chemical composition, nanostructure, and surface properties. The selection of an efficient synthesis process is a key factor that significantly influences the efficacy of the MONPs. The chemical synthesis of nanoparticles (NPs) via sol–gel route is an effective method to produce high-quality MONPs in comparison to other physical and chemical methods. Sol–gel synthesis is one of the simple, fastest and economically less expensive method, and has its own advantages like low processing temperature, homogeneity of the produced material and formation of the complex structures or composite materials. We believe that this detailed review will provide an insight into sol–gel synthesis of MONPs along with their characterization and diverse applications.