One-dimensional cobalt sulfide (CoS) acicular nanorod arrays (ANRAs) were obtained on a fluorine-doped
tin oxide (FTO) substrate by a two-step approach. First, Co
3O
4 ANRAs were synthesized, and then they were converted to CoS ANRAs for various periods. The compositions of the films obtained after various conversion periods were verified by X-ray diffraction, UV鈥搗isible spectrophotometry, and X-ray photoelectron spectroscopy; their morphologies were examined at different periods by scanning electron microscopic and transmission electron microscopic images. Electrocatalytic abilities of the films toward I
鈥?/sup>/I3鈥?/sup> were verified through cyclic voltammetry (CV) and Tafel polarization curves. Long-term stability of the films in I鈥?/sup>/I3鈥?/sup> electrolyte was studied by CV. The FTO substrates with CoS ANRAs were used as the counter electrodes for dye-sensitized solar cells; a maximum power conversion efficiency of 7.67% was achieved for a cell with CoS ANRAs, under 100 mW/cm2, which is nearly the same as that of a cell with a sputtered Pt counter electrode (7.70%). Electrochemical impedance spectroscopy was used to substantiate the photovoltaic parameters.
Keywords:
acicular nanorods; cobalt oxide; cobalt sulfide; counter electrode; dye-sensitized solar cell