Effect of graphene incorporation in carbon nanofiber decorated with TiO₂ for photoanode applications

The photovoltaic performance of dye-sensitized solar cells (DSSCs) using a photoanode fabricated with graphene incorporated carbon nanofibers with a TiO₂ layer on their surfaces is reported. The composite nanofibers were prepared through a process consisting of electrospinning and sol-gel process. The distribution of TiO₂ particles on the surface of the graphene-incorporated carbon nanofiber was characterized by scanning electron microscopy (SEM), and transmission electron microscopy (TEM). From the microscopic studies, we found that graphene plays a significant role to form TiO₂ particles on carbonaceous materials. Further studies on chemical composition using X-ray photoelectron spectroscopy reveal that different oxidation states of Ti in the synthesized titanium oxide were achieved by incorporating graphene in the nanofibers. Furthermore, TiO₂ synthetic conditions in the sol-gel process largely affected photovoltaic performance, particularly short circuit current; acidic conditions for the sol-gel process were more effective compared to neutral conditions. The incorporated graphene facilitates conducting charge carriers in TiO₂ by coordination with carbon, and increasing the adsorption of dye molecules owing to homogeneous distribution of TiO₂ along the nanofibers. This study further highlights the advantages of hybridizing different materials with 1D nanofiber geometry, offering a promising route to improving the resulting efficiency in light harvesting applications.