Abstract

Bojarite Mineral [Cu₃(trz)₃(μ₃-OH)]Cl₂.6H₂O was prepared at two temperatures (120 and 150 °C) by hydrothermal route for the first time. The sample was characterized by X-ray Diffraction (XRD), thermal analysis (TG/DTG) and Raman spectroscopy. The XRD analysis shows peaks attributed to Bojarite, crystallizing in a cubic structure. The Raman spectrum displays the characteristic bands of the Bojarite. The TG/DTG profile shows that the product contains water and organic matter, consistent with the nominal composition. A direct optical transition of gap Eg (=2.26eV), determined from the diffuse reflectance correspond to the transition O^2-:2p→Cu²⁺:t_2g. The photoelectrochemical has also been undertaken. Voltammetry in Na₂SO₄ solution (0.1M) exhibits low exchange current density (~2mAcm^{- 2}) and good electrochemical stability. The variation of interfacial capacitance versus potential is typical of n-type behavior with an electron density of 3.12×1016cm^-3 and a flat band potential (E_fb) of 0.17 VSCE. The Electrochemical Impedance Spectroscopy (EIS) shows only the bulk contribution in the dark (22kΩcm^-2), which decreases to 12.7kΩcm^-2 under visible irradiation supporting the semi conductivity. The positioning of the conduction and valence bands allows us to conclude that this material can be used in electrolysis.

Keywords:Bojarite; Hydrothermal synthesis; Thermal analysis; Photoelectrochemistry; Electrolysis