CoxMo(1−x)S2 intermixed reduced graphene oxide as efficient counter electrode materials for high-performance dye-sensitized solar cells

Abstract

In this study, nanocomposite electrocatalysts composed of cobalt molybdenum sulfide flower-like nanosheets intermixed with reduced graphene oxide (CoxMo(1−x)S2/rGO) were prepared by a facile one-step hydrothermal method and were used to prepare counter electrodes (CE) of high-performance dye-sensitized solar cells (DSSCs). The structural and morphological analysis of the nanocomposites were carried out using field emission scanning electron microscopy, micro-Raman, and X-ray photoelectron spectroscopies, which revealed 2-dimensional petal-like nanosheets of the ternary metal sulfides intermixed with the reduced graphene oxide sheets. The DSSCs fabricated using CoxMo(1−x)S2/rGO (CMS-2/rGO) as the counter electrode material exhibited power conversion efficiency (PCE) of 9.04%, which was found to be superior to the PCEs of DSSCs with CEs made of MoS2/rGO (7.56%), CoxMo(1-x)S2 (7.04–7.78%), and conventional Pt (8.72%). The electrochemical measurements showed that the excellent electrocatalytic activity of the CoxMo(1−x)S2/rGO on I3- can be attributed to the expanded active sites, improved charge transfer across the CE, and reduced electrode/electrolyte interface resistance. The facile preparation approach and outstanding catalytic behavior of CoxMo(1−x)S2/rGO indicate that the nanostructured CoxMo(1-x)S2/rGO intermix would be a cost-effective material over the platinum used in the CE of DSSCs.