Recent progress in zinc oxide nanomaterials and nanocomposites: From synthesis to applications

The global market of ZnO grows at an annual rate of 4.03%. ZnO has been used in a wide array of applications owing to its unique chemical, physical, and biological properties. In general, the properties of ZnO, such as band gap, crystallite size, and morphology, depend on the synthesis method and parameters employed. In this review, recent progress in the research on ZnO is presented. This review focuses on the latest advancements in pristine ZnO, doped ZnO, ZnO-based nanocomposites with other metal oxides, carbon-based materials, and spinels. The effect of the synthesis method and conditions on the properties of ZnO is discussed. In particular, recent studies on ZnO prepared through precipitation method, green synthesis, green combustion method, hydrothermal method, microwave-assisted hydrothermal, and sol–gel synthesis are reviewed. The effect of dopants and metal oxides on ZnO characteristics is also laid out. This review aims to provide the readers with a thorough understanding of structure–property relationships achieved by varying the synthesis parameters of ZnO, which will be beneficial for the fabrication of high-performance ZnO-based materials for photocatalytic, biological, gas sensing, and flexible electronic applications.