Nanocomposites of Co-NiS/GO as a Versatile Catalyst: Enabling Platinum-Free DSSC Counter Electrodes and Enhancing Organic Dye Degradation

This study presents the synthesis of a nanocomposite intended to serve as a counter electrode in dye-sensitized solar cells (DSSCs), replacing platinum electrodes, as well as functioning as a nanocatalyst for organic dye degradation. Graphene oxide was synthesized using a modified Hummers method, and cobalt-doped nickel sulfide on graphene oxide (Co-NiS/GO) was prepared via hydrothermal synthesis. The samples underwent characterization through various testing methods. X-ray diffraction analysis revealed a hexagonal structure with a crystallite size of 30 nm. Field-emission scanning electron microscopy/energy-dispersive X-ray images showed a cornflake-like structure, with elements such as cobalt, nickel, sulfur, carbon, and oxygen present. Chemical valence states were confirmed through X-ray photoelectron specteroscopy analysis. The power conversion efficiency of the Co-NiS/GO counter electrode in DSSCs was investigated, with parameters such as open-circuit voltage, short-circuit current density, fill factor, and power conversion efficiency calculated to be 8.6032 mV, 0.5484 mA cm⁻², 61, and 2.83%, respectively, based on I-V studies. Furthermore, the developed Co-NiS/GO nanocomposite was assessed for its photo catalytic dye degradation capabilities using malachite green (MG), achieving a degradation rate of approximately 96% within 180 min.