Fabrication of highly dispersed ultrafine Co9S8 nanoparticles on carbon nanofibers as low-cost counter electrode for dye-sensitized solar cells

Platinum is the most commonly used dye-sensitized solar cell (DSSC) counter electrode (CE) due to its superior electrocatalytic activity and high transparency. However, the scarcity and high-cost of Pt restrict its practical application for the large-scale production of DSSCs. Herein, a facile approach for fabricating highly dispersed Co 9 S 8 nanoparticles with small diameters in the range of 5–10 nm on the surface of carbon nanofibers (CNFs) via an electrospinning followed by calcination and hydrothermal reaction was developed. The composite material could be used as an efficient and low-cost Pt-free CE for DSSCs. The DSSC assembled with the prepared Co 9 S 8 /CNFs composite as a CE exhibited excellent electrocatalytic activity and a power conversion efficiency (PCE) of 8.37%, which is comparable to that of the DSSC with conventional thermally deposited Pt as the CE (8.50%). Therefore, the Co 9 S 8 /CNFs composite can be used as an efficient and low-cost promising alternative CE in DSSCs.