The air electrode, which reduces oxygen (O2), is a critical component in energy generation and storage applications such as fuel cells and metal/air batteries. The highest current densities are achieved with platinum (Pt), but in addition to its cost and scarcity, Pt particles in composite electrodes tend to be inactivated by contact with carbon monoxide (CO) or by agglomeration. We describe an air electrode based on a porous material coated with poly(3,4-ethylenedioxythiophene) (PEDOT), which acts as an O2 reduction catalyst. Continuous operation for 1500 hours was demonstrated without material degradation or deterioration in performance. O2 conversion rates were comparable with those of Pt-catalyzed electrodes of the same geometry, and the electrode was not sensitive to CO. Operation was demonstrated as an air electrode and as a dissolved O2 electrode in aqueous solution.

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Thin, adherent films of CdS were electrodeposited on FTO coated glass by reduction of a thiosulfate precursor in the presence of Cd(II) ions in methyltributylphosphonium (P(1,4,4,4)) tosylate ionic liquid at 130-150 degrees C. The structural properties of the deposits have been characterized by profilometry, scanning electron microscopy (SEM) and optical microscopy. Energy dispersive X-ray spectroscopy (EDX) was used to evaluate the chemical composition, which was found to be close to stoichiometric. Semiconductor properties including the band gap and flat band potential were calculated from UV-Vis and impedance spectroscopy measurements. The crystal structure was analyzed by X-ray diffraction (XRD). The data obtained from XRD and band gap measurements suggest the presence of hexagonal CdS crystals. The possible growth mechanism of the films is also addressed.