Cathodic reduction of iron(III) and copper(II) on various sulfide minerals in chloride solutions

An attempt has been made to correlate the kinetic data with published data on the semi-conducting properties of the metal sulfides. With the exception of covellite (which is not considered a semiconductor), the formal potentials of the copper(II)/copper(I) and iron(III)/iron(II) couples fall within the bandgaps of the metal sulfides and there does not appear to be any correlation between the energy levels of the couples in solution relative to the conduction bands of the sulfides and the reactivity for electron transfer to the metal ion couples. The effect of illumination with light of wavelength 405 nm on the cathodic currents has been demonstrated to be due to thermal and not photocurrent effects.