Highly electrocatalytic hybrid silver nanowire-graphene counter electrode for Co3+/2+ redox mediator based dye-sensitized solar cells

• Highly efficient hybrid silver nanowire-graphene counter electrodes for dye-sensitized solar cells.
• Homogeneous electrocatalytic sites were created by graphene platelets.
• Superior electrocatalytic properties of silver nanowire by graphene over coating in Co3+/Co2+ electrolyte.
• Low interfacial charge transfer resistance of silver nanowire-graphene based counter electrode.

Solution processed hybrid silver nanowire (AgNW)-graphene nanoplatelets (GNP) films were prepared and the electrocatalytic activity for the cobalt redox electrolyte in dye-sensitized solar cells (DSSCs) was examined. Cyclic voltammograms and Tafel polarization measurements confirmed the superior electrocatalytic activity of AgNW-GNP electrode than that of standard Pt counter electrode (CE). Electrochemical impedance spectroscopic (EIS) study also revealed the lower charge transfer resistance (Rct) of AgNW-GNP compared to Pt based CE. However, the resistance of the electrolyte diffusion was higher for the AgNW-GNP based CE resulted from the porous structure of the hybrid CE. The photoconversion efficiencies of the DSSC prepared with AgNW-GNP based CE was found to be 2.44%, which was comparable to that of Pt based DSSC, 2.55%. This study proposed an alternative low-cost cathode material for the cobalt redox mediator based DSSCs.

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