Pt-free counter electrode based on FeNi alloy/reduced graphene oxide in liquid junction photovoltaic devices

Abstract

This study presents a strategy to optimize FeNi nanoparticles (NPs) deposited onto reduced graphene oxide (RGO) in order to fabricate an efficient Pt-free counter electrode (CE) for use in a dye-sensitized solar cell (DSC). Nanohybrids exhibit a 3D network structure of RGO with high FeNi NP loading on the RGO surface. Well-dispersed Fe1-xNix (0 ≤ x ≤ 1) NPs ranging in size from 2 to 4 nm are stabilized with RGO after co-reduction of the metal precursor ions and graphene oxide. The developed catalysts are then applied as CEs in DSCs. As a result, the Fe0.7Ni0.3/RGO nanohybrid exhibited the highest electrocatalytic activity, corresponding to the lowest charge transfer resistance of 0.17 Ω, among the electrodes tested. The DSC employing Fe0.7Ni0.3/RGO CEs exhibits increases in efficiency of 87.68% and 75.65% relative to those of Fe0Ni1/RGO and Fe1Ni0/RGO devices, respectively, due to the optimization of the charge-transfer resistance and the reduced diffusion impedance values of the developed materials. This strategy is simple and efficient for fabricating cost-effective CE materials utilized in DSCs and fabricating efficient catalysts to facilitate methanol oxidation and oxygen reduction reactions.