Studies on synergetic effect of rGO-NiCo2S4 nanocomposite as an effective counter electrode material for DSSC

Abstract Nanocomposites of reduced graphene oxide (rGO) and NiCo 2 S 4 with different amount of graphene oxide (GO) are synthesized through a one- step solvothermal method and their catalytic activity towards I - /I 3 - redox electrolyte for dye-sensitized solar cell (DSSC) application are reported. The growth mechanism of the pristine hierarchical marigold like microspheres of NiCo 2 S 4 that formed without rGO and the nanocomposite of rGO-NiCo 2 S 4 are also proposed. Electrochemical studies confirmed the synergetic effect of nickel and cobalt ions with the high electrical conductive rGO networks that enhance the electrocatalytic activity of NiCo 2 S 4 nanostructures. The synergistic effect between NiCo 2 S 4 and rGO may be attributed to the higher conductivity of rGO and the inverse spinel crystal structure of NiCo 2 S 4 that have more octahedral catalytic active sites of Co 3+ . The amount of graphene oxide plays the important role of controlling the DSSC performance and the power conversion efficiency. The efficiency achieved for the rGO-NiCo 2 S 4 counter electrode (CE) based DSSC is 8.15%, which is remarkably higher than that of pristine NiCo 2 S 4 (7.36%), and Pt (7.23%) under the same experimental conditions.