Transition Metal Nitrides Are Heating Up the Field of Plasmonics

Metal nitride nanostructures have been predicted to exhibit plasmonic responses in the UV to IR region, which can enable their potential use as low-cost, chemically, and thermally stable materials in several applications. In the case of photothermal applications, nitrides have been shown, both numerically and experimentally, to perform better than the noble metals. Additionally superior thermal stability of the metal nitride materials offers compatibility with high temperature device fabrication techniques. The plasmon frequency for transition metal nitride materials can be tuned from the UV to IR region by varying the type of metal in the nitride and metal/nitrogen ratio. Recently, studies have focused on developing and applying free-standing metal nitride nanostructures. Most investigations have focused on TiN, but as of late focus has been shifting to investigate other nanostructured nitrides such as ZrN and HfN. This Perspective will highlight recent key findings on the synthesis of plasmonic metal nitrides; associated thermal stability and photothermal properties; and application in photothermal therapy, solar-driven water evaporation, and chemical reactions. An outlook on current knowledge gaps and challenges and future directions to further this field is also presented.