A comprehensive review on ZnO wide-bandgap semiconductors: Materials engineering, properties, and emerging applications

We report on water splitting, disinfection, and pollutant degradation processes assisted by photocatalysis supported by zinc oxide (ZnO) under varied experimental and environmental conditions. In addition, the role of ozonation in the presence of ZnO and its synergistic impact on the effective elimination of organic and inorganic contaminants is discussed, highlighting enhanced reaction kinetics and mineralization efficiency. ZnO nanoparticles (ZnO-NPs) have also emerged as appropriate and versatile tools in drug delivery systems and chemical or biological sensing applications due to their biocompatibility, tunable surface chemistry, and strong photoluminescence response. Owing to its distinctive structural, optical, and electronic properties, ZnO has been extensively employed as an n-type inorganic semiconductor in organic solar cells (OSCs) and hybrid solar cells (HSCs), where it functions efficiently as an electron transport and hole-blocking layer. Its high chemical and thermal stability, non-toxicity, facile synthesis routes, low production cost, and excellent optoelectronic characteristics make ZnO highly attractive for large-scale technological applications. Furthermore, ZnO is widely used as a preservative and functional additive in numerous products and materials, including foundations, ceramics, glass, rubbers, lubricants, plastics, cement, ointments, paints, adhesives, sealants, colorants, ferrites, foods, batteries, food enhancers, fire-retardant systems, and first-aid tapes. These diverse applications underscore the multifunctional nature and industrial relevance of ZnO-based materials.