Unveiling the Future Frontiers of ZnO, Fundamental Mechanism, Frontier Advances in Material Fabrication, and Characterization: Photocatalytic and Advanced Biomedical Applications

Energy crises, environmental pollution, and diverse medical issues are the main spots for research currently. To deal with these issues, materials chemistry provides materials with diverse architectures and functionalities. ZnO is the one of the most studied materials with enormous applications in energy production and storage, environmental purification, gas sensing, and biomedical treatment. This review has discussed the electronic and crystal structure of ZnO semiconductor. Different techniques such as hydrothermal, solvothermal, sol–gel, chemical vapor deposition, electrochemical deposition, sonochemical, and microwave methods are mentioned to provide a broad range of fabrication techniques. Further, this study discussed some well‐known characterization techniques such as X‐ray diffractometry, X‐ray photoelectron spectroscopy, photoluminescence spectroscopy, and Raman spectroscopy to follow the structure and morphology of ZnO nanocrystals. The effects of the different types of defects on the morphology of ZnO are highlighted in detail. The applications of ZnO nanocrystals in energy production and environmental purification are highlighted to demonstrate their significant role in these field. Anticancer, antifungal, antibacterial, and antidiabetic activities are discussed to highlight the diverse biomedical applications of ZnO nanoparticles. Finally, research gaps and future perspectives are discussed. Although several review articles have discussed the activity of ZnO nanocrystals, this article highlights either the photocatalytic or biomedical applications only.