A frontier Zn- and N-rich complex grafted onto reduced graphene oxide for the electrocatalysis of dye-sensitized solar cells

Abstract

This paper proposes a novel μ-hydroxo-bridged dinuclear macrocyclic zinc complex, {[Zn(C₁₀H₂₀N₈)]₂(OH)}(BF₄)₃. The structure was determined by X-ray crystallography: Monoclinic, C2/c, a = 25.4632(6), b = 10.9818(3), c = 15.7522(4) Å, Z = 8, R₁ = 0.0233, wR₂ = 0.0557, based on reflections I > 2σ(I). The complex was successfully reacted with graphene oxide to form a μ-hydroxo-bridged dinuclear macrocyclic Zn complex/reduced graphene oxide composite. To evenly disperse the Zn- and N-rich complex onto the surface of the reduced graphene oxide, and to enhance the electrocatalytic property of the graphene composites, a soluble molecular grafting method was used here. The graphene-based composites were applied as the counter electrodes (CEs) of dye-sensitized solar cells. Current density–voltage measurements revealed that the conversion efficiency of the GO/Zn (1 : 10) sample was 7.78%, which was better than that of Pt CE (7.49%). GO/Zn (1 : 10) CE exhibited the lowest impedance (R_CE = 9.90 Ω), which was better than that of Pt CE (R_CE = 66.1 Ω), showing that GO/Zn CEs can reduce the impedance at the CE/electrolyte interface. The proposed method is simple, and the composite materials can potentially replace conventional Pt, optimizing efficiency and reducing production cost.