Influence of Nickel Content in CoxNiyS Nanoparticles as an Efficient Catalyst and its Applications in Solar and Fuel Cells

A novel approach for the synthesis of CoxNiyS nanoparticles on fluorine-doped tin oxide and Ni-foam substrates for methanol oxidation in alkaline media is described. The introduced electrocatalyst was synthesized using different concentrations of Co and Ni via a simple and effective process; the electrochemical properties were assessed by cyclic voltammetry. The Co90%Ni10% catalyst showed a current density of -0.576 and -0.801 mA on FTO and Ni-foam, respectively, which is the best for the oxygen reduction reaction. The observed electrocatalytic activity proves that the Ni content plays a crucial role in the enhanced current density. Co90%Ni10% also showed superior stability; 78.75% of the electroactive area remained compared to 67.31% in the case of Co0%Ni100% on Ni-foam. Moreover, the optimized catalyst was used as a counter electrode (CE) in quantum-dot sensitized solar cells and showed greater catalytic activity in a polysulfide redox electrolyte than Pt based CEs. As a result, under 1 sunlight illumination, Co90%Ni10% exhibited a power conversion efficiency up to 2.89%, which was much higher than that of the Pt-based CEs (1.32%). The PCE of Co90%Ni10% was enhanced by the surface morphology, roughness factor, and current density, which permit prompt electron transport and lowers the charge transfer resistance rate for the polysulfide redox electrolyte.