Dye-sensitized solar cells (DSC cells) have attracted extensive attention since its invention by Grätzel in 1991 as a potential alternative to silicon solar cells due to the ease of fabrication and the relative low cost. . Existing DSC cells generally use Pt as counter electrode (CE) because Pt possesses excellent catalytic activity for I3- reduction. Nonetheless Pt can be corroded by electrolyte with time. In the meantime, the high cost and scarcity of Pt makes it a less desirable candidate for use in industry. Carbon based materials including graphite, graphene, carbon black, carbon nanotube, and carbon nanofibers have been investigated as an alternative to Pt because of their strong catalytic effect, high electrical conductivity, and corrosion resistance.
An innovative nanomaterial for CE of DSC cells was developed by integrating graphene into carbon nanofibers through electrospinning followed by growing Pt nanoparticles on nanofiber surface through a redox reaction. Graphene-embedded carbon nanofibers (GCNFs) were produced by electrospinning polyacrylonitrile (PAN) with graphene nanoplatelets followed by stabilization and carbonization. GCNFs with high loading surface-attached platinum nanoparticles (GCNFs-PtNPs) were subsequently prepared by redox reaction and spray-deposited onto fluorine doped tin dioxide (FTO) glass as counter electrode (CE) for dye sensitized solar cells (DSC cells). Graphene in carbon nanofibers and Pt nanoparticles on carbon nanofiber surface demonstrated synergistic effect on performance of DSC cells as this hierarchical nanomaterial GCNFs-PtNPs was employed as CE in DSC cell. Compared to DSC cell with conventional Pt CE, the DSC cell with GCNFs-PtNPs CE showed significant improvement in solar energy conversion efficiency, which reached ~10 %. This is the highest conversion efficiency so far with carbon nanofiber based CE. Our research established an economic approach to acquire decent CE materials for super efficiency DSC cells.