TITLE:
Electrochemical Characteristics of Natural Mineral Covellite
AUTHORS:
Mirjana Rajčić-Vujasinović, Zoran Stević, Sanja Bugarinović
KEYWORDS:
Covellite; Capacitance; Copper Sulfides; Electrochemical Characterization; Solar Cells
JOURNAL NAME:
Open Journal of Metal,
Vol.2 No.3,
September
4,
2012
ABSTRACT: Electrochemical characteristics of covellite (CuS) are of importance from flotation and metallurgical point of view, as well as due to its potential application in solid state solar cells and in photocatalytic reactions. Also, the compound CuS appears as an intermediary product or a final product in electrochemical oxidation reactions of chalcocite (Cu2S) which exhibits supercapacitor characteristics. Natural copper mineral covellite has been investigated in inorganic sulfate acid electrolytes, as well as in strong alkaline electrolyte. Physical properties of covellite were characterized by X-ray diffraction (XRD) and the active surface was examined by optical and electron microscopy (EM) before and after oxidation in galvanostatic regime. Different electrochemical methods (galvanostatic, potentiostatic, cyclic voltammetry and electrochemical impedance spectroscopy - EIS) have been used. The capacitance of around 21 Fcm-2 (geometric area), serial resistance of about 90 Ωcm2 and leakage resistance of about 1200 Ωcm2 have been measured in 1 M H2SO4. The addition of cupric ions in sulfate electrolyte leads to the significant increasing of the capacitance, but having the increase of self-discharge as a negative side phenomenon. The capacitance of around 6.7 Fcm-2 (geometric area), serial resistance of about 80 Ωcm2 and leakage resistance of about 380 Ωcm2 have been measured in 6 M KOH.