FeS2 nanoplates embedded in rGO sheets: A novel nanostructured counter electrode for enhanced DSSC efficiency

Abstract

Transition metal sulfides (TMS) have gained significant attention as cost-effective, platinum-free alternatives for counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). This work presents a novel nanohybrid composed of hexagonal FeS₂ (iron pyrite) nanoplates integrated onto reduced graphene oxide (rGO) sheets as an efficient CE for DSSCs. The nanohybrid was synthesized through a facile one-step solvothermal process and thoroughly characterized, revealing the formation of uniformly distributed crystalline FeS₂ nanoplates (1 μm in length and 70 nm in thickness) intricately embedded onto the rGO surface. This innovative FeS₂/rGO hybrid demonstrated an impressive power conversion efficiency (PCE) of 6.23 %, significantly outperforming the 4.63 % PCE of standalone FeS₂ nanostructures and even exceeding the 5.89 % efficiency achieved by the conventional Pt-based DSSC. The superior performance is attributed to the synergistic effect of the catalytically active FeS₂ nanoplates and the electrically conductive two-dimensional rGO framework. This unique architecture enhances the density of catalytically active sites and accelerates ion diffusion pathways, leading to outstanding electrocatalytic activity for triiodide reduction. These results highlight the FeS₂/rGO nanohybrid's potential as a highly efficient and sustainable alternative to traditional platinum-based CEs in DSSCs.