Pt-free and efficient counter electrode with nanostructured CoNi2S4/rGO for dye-sensitized solar cells

Abstract

Solar cells of the third generation aim to reduce costs and/or boost the efficiency of current solar cells. The goal of this paper is to systematically research a cobalt nickel sulfide/reduced graphene oxide (CoNi2S4/rGO) nanocomposite sandwich type dye sensitized solar cell (DSSC) prototype as a counter electrode synthesized by a simple one-step hydrothermal process. The structural and morphological characterization of the nanocomposite reveals that cubic structure with spherical shaped nanoparticles (25–30 nm), which is uniformly decorated on the rGO sheets. When used as a counter electrode, the optimized CoNi2S4/rGO nanohybrid film delivers a high photo-conversion efficiency of 10.21%, which is higher than that theDSSCmanufacturedascounterelectrodewithPt (6.45%) and even better than that with pristine CoNi2S4 (3.45%). Cyclic voltammetry, Tafel plot and electrochemical impedance spectroscopy show that the as-synthesized CoNi2S4/rGO nanohybrid counter electrode exhibits an excellent electrocatalytic property than compared with pure CoNi2S4 counter electrode (CE). This research also offers some clues to the potential growth and rational design of CoNi2S4/rGO nanohybrid counter electrode for advance energy applications.