Ultrafast Mechanochemical Synthesis of Plasmonic Transition Metal Nitride Nanoparticles.

Refractory plasmonic materials, such as transition metal nitrides and carbides have shown the potential to replace more expensive or oxidatively and thermally unstable materials composed of gold, silver, aluminum, and copper. The synthesis of transition metal nitride nanoparticles typically relies on high-temperature (>800°C) nitridation of metal halides or oxides, ranging from hours to even days. These methods are slow and consume significant amounts of energy. Herein, a rapid, mechanochemical method with no need for external heating is presented, showing effective formation of plasmonic group 4 transition metal nitride nanoparticles in as little as 60 seconds of grinding. Using this method, both mono- (TiN, ZrN, and HfN) and mixed-metal nitrides (ZrxHf1-xN, 0<x<1) can be achieved. The particles were analyzed using powder x-ray diffraction, x-ray photoelectron spectroscopy, electron microscopy, and absorbance spectroscopy. The effect of nitride source, milling time, and milling frequency on the product formation, particle size, crystallinity, and localized surface plasmon resonance were studied.