An overview of metal hydroxyfluoride–A novel semiconductor material

Semiconductors have been widely used in many high-tech fields such as photo- and electro-catalysis, ion batteries, and solar cells. In addition to the earliest discovered elemental and compound semiconductors, such as monocrystalline silicon and metal oxides, new types of compound semiconductors have been discovered. Among them, metal hydroxyfluorides (MOHF) are an emerging type of semiconductor that are easy to synthesize and inexpensive. However, many of their properties and applications are not well understood. Nevertheless, some MOHF materials, such as ZnOHF and CoOHF, have been sufficiently developed, and their applications have been extensively explored. This review focuses on a new compound semiconductor, MOHF, with ZnOHF and CoOHF as the typical. After a short introduction to their physical and chemical properties, their common applications are illustrated with several examples. Subsequently, other less-researched MOHF and MOHF-like materials, as well as their applications, are discussed. Moreover, the expectations and development directions of MOHFs are briefly summarized.