Morphology-controlled fabrication of NiCo2S4 nanostructures decorating carbon nanofibers as low-cost counter electrode for efficient dye-sensitized solar cells

The development of highly efficient, earth-abundant and low-cost counter electrode materials is of significant importance and challenge for practical application in dye-sensitized solar cells. In this work, morphology-controlled NiCo 2 S 4 nanoparticles (NPs) and nanorods (NRs) decorating carbon nanofibers (CNFs) have been prepared via an electrospinning and hydrothermal or solvothermal strategy, which are further utilized as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). Benefitting from the rich nickel and cobalt ions redox chemistry and more exposed catalytically active sites from NiCo 2 S 4 NRs grown vertically on the surface of CNFs as well as faster electron transporting capability providing by the highly conductive CNFs, the DSSC device based on NiCo 2 S 4 NRs/CNFs CE yields an excellent power conversion efficiency of 9.47%, which is higher than that of the devices with NiCo 2 S 4 NPs/CNFs (8.63%), Pt (8.18%) and CNFs (6.06%) as CEs under AM 1.5 G irradiation. Furthermore, the NiCo 2 S 4 NRs/CNFs CE shows an excellent electrochemical stability in an iodine-based electrolyte. This study highlights a controllable and versatile route to rational design efficient counter electrode catalysts for high-performance CEs application.