Synthesis and characterization of Cu3Se2 nanofilms by an underpotential deposition based electrochemical codeposition technique

The Cu₃Se₂ nanofilms were synthesized with underpotential deposition based electrochemical codeposition technique for the first time in the literature. The electrochemical behaviors of copper and selenium were investigated in 0.1 M H₂SO₄ on Au electrode. The effects of concentration and scan rate on the electrochemical behavior of selenium were studied. The electrochemical behaviors in underpotential deposition and bulk regions of the Cu-Se system were investigated in acidic solution by cyclic voltammetry and electrolysis techniques. X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, X-ray diffraction, Raman spectroscopy, and ultraviolet and visible absorption spectroscopy techniques were used for characterization of synthesized films. According to the X-ray photoelectron spectroscopy spectrum, Cu/Se ratio was determined to be approximately 3/2. Copper selenide nanofilms are two phases and polycrystalline according to X-ray diffraction. The films mainly formed tetragonal Cu₃Se₂ (umangite mineral structure) structure and the particle size was approximately 45.95 nm. Scanning electron microscopy images showed that Cu₃Se₂ nanofilms consisted of uniform, nano-sizes and two-dimensional. It was found through AFM that the surface roughness of the film was 6.173 nm, with a mean particle size of around 50 nm. Depending on the deposition time, the band gaps of the Cu₃Se₂ films were in the range of 2.86–3.20 eV. Three characteristic vibrational modes belonging to Cu₃Se₂ nanofilms were recorded in the Raman spectrum.