ZnO tetrapod materials for functional applications

In the last 15 years, more than 50,000 papers with zinc oxide (ZnO) in the title are listed within ISI database. The outstanding popularity of ZnO has many reasons; the most important one appears to be its multi-functionality, resulting in applications in physics, chemistry, electrical engineering, material science, energy, textile, rubber, additive manufacturing, cosmetics, and pharmaceutical or medicine, as well as the ease to grow all kinds of nano- and microstructures. A key structure is the tetrapod-shaped ZnO (T-ZnO), which we want to focus on in this mini-review to demonstrate the remarkable properties and multifunctionality of ZnO and motivate why even much more research and applications are likely to come in near future. As T-ZnO came into focus again mainly during the last 10 years, the big data problem in T-ZnO is not as severe as in ZnO; nevertheless, a complete overview is impossible. However, this brief T-ZnO overview attempts to cover the scopes toward advanced technologies; nanoelectronics/optoelectronics sensing devices; multifunctional composites/coatings; novel biomedical engineering materials; versatile energy harvesting candidates; and unique structures for applications in chemistry, cosmetics, pharmaceuticals, food, agriculture, engineering technologies, and many others. The 3D nanotechnology is a current mainstream in materials science/nanotechnology research, and T-ZnO contributes to this field by its simple synthesis of porous networks as sacrificial templates for any desired new cellular materials.