Electrocatalytic Reduction of Carbon Dioxide using Sol-gel Processed Copper Indium Sulfide (CIS) Immobilized on ITO-Coated Glass Electrode

Sol-gel processed copper indium sulfide (CIS) films have been processed on glass and transparent indium doped tin oxide (ITO)-coated glass electrodes by a straightforward layer by layer spin coating route yielding excellent film qualities with subsequent thermal annealing. Resulting films were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-vis spectroscopy. We apply these films in an electrochemical cell as a working electrode and take a view on the reduction of carbon dioxide (CO2) to its energy richer carbon monoxide (CO) in acetonitrile solution containing 0.1 M (C4H9)(4)NPF6 supporting electrolyte saturated with CO2. CIS films exhibit pronounced electrochemical and photoelectrochemical activities. Concomitantly, we quantify the generation of CO, which starts to evolve at a threshold potential of -0.60 V vs normal hydrogen electrode (NHE). The calculated faradaic efficiency of the electrochemical reduction of CO2 into CO exceeds 20 (+/- 1)% in an optimized thin-film structure.