Surveying the Synthesis, Optical Properties and Photocatalytic Activity of CuN Nanomaterials.

This review addresses the most recent advances in the synthesis approaches, fundamental properties and photocatalytic activity of CuN nanostructures. Herein, the effect of synthesis conditions, such as solvent, temperature, time and precursor on the precipitation of CuN and the formation of secondary phases of Cu and CuO are surveyed, with emphasis on shape and size control. Furthermore, CuN nanostructures possess excellent optical properties, including a narrow bandgap in the range of 0.2 eV-2 eV for visible light absorption. In that regard, understanding the effect of the electronic structure on the bandgap and on the optical properties of CuN is therefore of interest. In fact, the density of states in the d-band of Cu has an influence on the band gap of CuN. Moreover, the potential of CuN nanomaterials for photocatalytic dye-degradation originates from the presence of active sites, i.e., Cu and N vacancies on the surface of the nanoparticles. Plasmonic nanoparticles tend to enhance the efficiency of photocatalytic dye degradation of CuN. Nevertheless, combining them with other potent photocatalysts, such as TiO and MoS augments the efficiency to 99%. Finally, the review concludes with perspectives and future research opportunities for CuN-based nanostructures.