Hydrothermal production of low-cost CeNi2S4-reduced graphene oxide composites as an efficient counter electrode for high performance dye-sensitized solar cells

Dye sensitized solar cell (DSSC) technology could become a low-cost solution for solar energy harvesting if the use of expensive dyes and Pt can be avoided. This work reports the development of a novel nanohybrid based on CeNi2S4 nanotubes embedded on sheets of reduced graphene oxide (RGO), which can serve as excellent counter electrode for DSSC showing great promise to replace Pt. The structural and morphological characterization of the nanocomposite synthesized using a simple one step hydrothermal method revealed well defined crystalline nanotubes of CeNi2S4 (with length 190 nm and diameter 8.54 nm) uniformly embedded on the surfaces of the RGO sheets (∼2.65 μm in size). The morphology and size of the nanotubes were found to be dependent on the duration of the hydrothermal reaction. The optimized CeNi2S4/RGO nanohybrid CE when used as counter electrode in DSSC, photo conversion efficiency as high as 9.21 ± 0.03 % was recorded, a value almost equal to that obtained from the DSSC fabricated with Pt as counter electrode and much higher than that with bare CeNi2S4 justifying its potential use in Pt-free DSSC. The improved performance of the electrode have been attributed to the hierarchical nanohybrid structure consisting of catalytically active 1D CeNi2S4 nanotubes embedded on electrically conducting 2D RGO sheets that provides fast ion diffusion pathways, large accessible surface area and good chemical and thermal stability.