Aspects of the Interfacial Electrochemistry of Semiconductor Pyrite  ( FeS2 )

Abstract

The electrochemical oxidation of has been studied using cyclic voltammetry, EDX, and AES techniques. Cyclic voltammograms reveal one anodic peak and two cathodic peaks on the return sweep. These peaks are attributed to the electroadsorption/desorption of OH groups on pyrite surfaces. It is proposed that the electrocatalytic electroadsorption of OH groups on is due to the presence of Fe 3d electrons in the upper portion of the valence band. Thus, OH− ions are oxidized by holes on Fe 3d states in the first step. These groups are transferred to sites in the second step. Surface analysis reveals preferential release of Fe2+ from the pyrite lattice. A mechanism for the anodic dissolution of pyrite is proposed, according to which S is not an intermediate product, but is rather a stable end product which forms due to the decomposition of thiosulfate . The proposed mechanism is consistent with the observations reported by previous investigators.