Preparation of copper nitride nanoparticles using urea as a nitrogen source in a long-chain alcohol

We previously reported a safe and easy method for the synthesis of copper nitride nanoparticles from copper acetate monohydrate and ammonia gas in a long-chain alcohol solvent. Here, we report the development of a method for synthesizing copper nitride nanoparticles without the use of ammonia, which is toxic and corrosive. Specifically, copper nitride nanoparticles were synthesized by reaction between copper acetate monohydrate and urea in 1-nonanol as a solvent. We investigated the influence of the amount of urea on the crystal phases and morphology of the particles. Using five equivalents of urea relative to the copper ion concentration, we obtained copper nitride nanoparticles with diameters of approximately 150 nm. When less urea was used, a cuprite (Cu₂O) phase was formed as a byproduct. The nanoparticle powders obtained by the developed method were characterized by powder X-ray diffraction analysis, transmission electron microscopy, and diffuse reflection spectroscopy.