Zinc Molybdate-carbon Composites as Counter Electrode Materials for Dye-sensitized Solar Cells

Abstract

Sheet-like structured zinc molybdate (ZnMoO4) was firstly synthesized by hydrothermal method. Then, graphite (G) and conductive carbon (Cc) modified ZnMoO4 (denoted as ZnMoO4-G and ZnMoO4-Cc) were fabricated by dispersing ZnMoO4 into graphite (G) and conductive carbon (Cc) solutions, respectively. The obtained ZnMoO4-G and ZnMoO4-Cc composites were used as electrocatalysts for dye-sensitized solar cells (DSCs), exhibiting promising potential as counter electrode materials. The experimental results demonstrated that the DSC assembled with sole ZnMoO4 showed an overall light conversion efficiency of 4.19%, while the DSCs made of ZnMoO4-G and ZnMoO4-Cc counter electrodes displayed power conversion efficiencies of 6.56% and 7.36%, respectively. The solar cell performance obtained by ZnMoO4-Cc counter electrode was comparable to Pt-based DSCs (7.81%). Various characterization techniques, such as electrochemical impedance spectra (EIS), cyclic voltammetry (CV) and Tafel polarization curve, were employed to evaluate the electrocatalytic activity of all investigated materials. Among all investigated counter electrodes, the high solar cell performance obtained by ZnMoO4-Cc counter electrode could be attributed to superior electrical conductivity of conductive carbon material and excellent 1134 无 机 材 料 学 报 第 29 卷 electrocatalytic activity of sheet-like structured ZnMoO4-Cc.