SEMICONDUCTOR ELECTROCHEMISTRY OF PARTICULATE PYRITE - DISSOLUTION VIA HOLE AND ELECTRON PATHWAYS

Electrochemical and photoelectrochemical experiments were conducted to investigate the pyrite/aqueous interface reaction by using microparti cles of synthetic pyrite as electrodes. The potential of the conductio n bandedge of pyrite as a function of pH was estimated to be E(c) = 0. 34 - 0.059 pH in volts us. saturated calomel electrode (SCE). The open -circuit potential of pyrite electrode in 1 M HNO3 solution was 0.38 V -SCE. Illumination of pyrite microelectrodes increased the anodic curr ent and the dissolution rate dramatically but had little effect on the cathodic current and the cathodic dissolution. These results indicate that pyrite, as an n-type semiconductor, dissolves anodically through a hole transfer (valence band) pathway, while cathodic dissolution on ly involves electron reaction (conduction band).