An innovative catalyst design as an efficient electro catalyst and its applications in quantum-dot sensitized solar cells and the oxygen reduction reaction for fuel cells

Abstract

A novel approach for the synthesis of Co_xNi_yS nanoparticles on fluorine-doped tin oxide (FTO) and nickel-foam (Ni-foam) substrates for methanol oxidation in alkaline media is described. The introduced electrocatalyst was synthesized using different concentrations of cobalt (Co) and nickel (Ni) via a simple and effective process; the electrochemical properties were assessed by cyclic voltammetry. The Co_90%Ni_10% 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. Co_90%Ni_10% also showed superior stability; 78.75% of the electroactive area remained compared to 67.31% in the case of Co_0%Ni_100% 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 CuS and Pt based CEs. As a result, under 1 sun illumination, Co_90%Ni_10% exhibited a power conversion efficiency of up to 2.89%, which was much higher than that of the Pt (1.32%) and CuS (2.03%) CEs. The power conversion efficiency of Co_90%Ni_10% was enhanced by the surface morphology, roughness factor, and current density, which permit prompt electron transport and lower the charge transfer resistance rate for the polysulfide redox electrolyte.