This is a comprehensive book that explores the various aspects of metal-doped ZnO nanostructures, including their synthesis, structure, and applications in catalysis. The book covers a wide range of topics related to ZnO nanoparticles, such as Chemical Vapor Deposition, Hydrothermal Method, Solvothermal Method, Sol-Gel Method, Physical Vapor Deposition, Atomic Layer Deposition, Templating Method, and more. The book also delves into the various applications of metal-doped ZnO nanostructures in photocatalysis, heterogeneous catalysis, homogeneous catalysis, photodegradation, water purification, gas sensing, and biosensing. It discusses the use of nanosensors in various applications and the modification of the surface of metal-doped ZnO nanostructures with ligands and surfactants. Additionally, the book highlights the importance of morphology control, crystal growth, and defect engineering in the development of metal-doped ZnO nanostructures with desired properties. It describes various structures, including nanorods, nanowires, nanotubes, nanosheets, nanoplates, core-shell structures, hybrid structures, dendritic structures, and porous structures. The book also covers the latest advancements in single-atom catalysts, bimetallic catalysts, multimetallic catalysts, supported catalysts, self-supported catalysts, photovoltaics, and energy conversion. Overall, this book is a valuable resource for researchers, engineers, and students who are interested in the synthesis, structure, and catalytic applications of metal-doped ZnO nanostructures.