Oxidation kinetics of ultrasmall colloidal chalcopyrite (CuFeS2) with one-electron oxidants

Abstract

The stopped flow technique has been used to study the oxidation of ultrasmall colloidal chalcopyrite (CuFeS2) particles (diameter 50-90 Å) by the one-electron oxidants hexacyanoferrate(III) (Fe(CN)63-) and hexachloroiridate(IV) (IrCl42-) in aqueous solution. The stoichiometry of the initial oxidation step corresponds to the reaction CuFeS2(s) + 5H2O → Cu(OH)2(s) + Fe(OH)3(s) + 2S0(s) + 5H+ + 5e-. Further oxidation of the elemental sulfur results in the formation of S2O32- and SO42- in solution, as determined by ion chromatography. Time-resolved measurement of both the oxidant and chalcopyrite concentrations has provided a detailed understanding of the mechanism involved in the oxidation of c..