Synthesis, characterization and performance as a Counter Electrode for dye-sensitized solar cells of CoCr-decorated carbon nanofibers

The study introduces novel Co/Cr-decorated carbon nanofibers to be used as an effective counter electrode in the dye-sensitized solar cells. The decorated carbon nanofibers were prepared by a simple technique; electrospinning. Typically, calcination of electrospun nanofibers composed of cobalt acetate, chromium acetate and poly vinyl alcohol in argon atmosphere results in producing carbon nanofibers decorated by CoCr nanoparticles. The crystallinity, purity and morphology of the introduced nanofibers were inspected by scanning electron microscope (SEM), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), X-ray diffractometer (XRD), TEM mapping and line TEM EDX. These characterization techniques affirmed the formation of good morphology carbon nanofibers decorated by Co/Cr nanoparticles. Cyclic voltammetry technique indicated that the modified carbon nanofibers have a high performance to reduce iodine to iodide ions with strong dependence of the redox peaks intensities on the scan rate which indicates high reversibility and simultaneously supports exploiting these nanofibers as a counter electrode in the dye sensitized solar cells (DSSCs). Accordingly, the DSSC based on utilizing the introduced nanofibers as counter electrode exhibits good performance; photovoltaic conversion efficiency of 3.27%, open circuit voltage of 0.685 V and a short-circuit current density of 8.784 mA/cm2. Moreover, electrochemical impedance spectroscopy (EIS) analysis revealed low electrical resistance of the counter electrode. From these results, the synthesized Co/Cr-decorated carbon nanofibers can be considered as a promising Pt-free counter electrode for dye sensitized solar cells.