Colloidal Synthesis and Photocatalytic Properties of Cu3NbS4 and Cu3NbSe4 Sulvanite Nanocrystals

Niobium sulvanites Cu₃NbX₄ (X = S, Se) have been theoretically predicted as promising candidates for solar photovoltaics and photocatalytic water splitting. This report outlines the first synthesis of Cu₃NbS₄ and Cu₃NbSe₄ in a nanocrystalline form. The crystal structures were investigated by X-ray diffraction, identity was confirmed by Raman spectroscopy, and the optoelectronic properties and morphology of Cu₃NbS₄ and Cu₃NbSe₄ nanocrystals were examined by UV–vis spectroscopy and transmission electron microscopy, respectively. To gain insight into the Cu₃NbX₄ formation, a mechanistic study was conducted for Cu₃NbSe₄ monitoring the nanoparticles’ formation as a function of reaction time. Methylene blue photodegradation tests were conducted to evaluate the photoactivity of Cu₃NbS₄ and Cu₃NbSe₄. The degradation rates, 2.81 × 10^–2 min^–1 and 1.22 × 10^–2 min^–1 proved the photocatalysts’ potential of nanoscale Cu₃NbX₄.