Dissolution of platinum in methoxy propionitrile containing LiI/I2

The stability of vapour deposited Pt and Pd as electrocatalysts on fluorine doped, tin oxide coated glass for the use as counter electrodes in dye senzitized electrochemical solar cells has been investigated. The electrocatalytically active layers did not seem to be chemically stable in an electrolyte consisting of LiI and I2 dissolved in methoxy propionitrile. Thermodynamical calculations suggest the dissolution of Pt and Pd from the electrode surface to be caused by the formation of PtI4 and PdI6. Formation of complex species as PtI2−4 and PdI2−4 is less thermodynamically favoured, but PtI2−4 may also be present in the solution.