Ni–Co bimetallic nanoparticles anchored reduced graphene oxide as an efficient counter electrode for the application of dye sensitized solar cells

The bimetallic Ni–Co nanoparticles anchored reduced graphene oxide (rGO) nanocomposite was prepared by one-pot chemical reduction technique and utilized as an efficient counter electrode in dye sensitized solar cells (DSSC). The spherical shaped Ni–Co nanoparticles with the average diameter of 8 nm were uniformly anchored over the surface of rGO sheets and its face centered crystalline structure was explored by the diffraction patterns. The structural interaction exerted between the active carbon support and bimetallic nanoparticles was evaluated by using Fourier Transform Infrared analysis. rGO/Ni–Co composite exhibited the maximum electroreduction toward I₃ ⁻/I⁻ as evidenced from the cyclic voltammetric studies, owing to the synergetic effects of rGO sheets and Ni–Co bimetallic nanoparticles. Furthermore, rGO/Ni–Co counter electrode equipped DSSC exhibited the maximum solar to electrical energy conversion efficiency (η) of 3.10 % under 1 sun illumination with the fill factor (FF) of 0.48. The time and cost efficient preparation technique associated with the better electrochemical properties and high power conversion efficiency observed for the rGO/Ni–Co counter electrode demonstrated its potential utilization in DSSCs.