Three-dimensional vertically aligned hybrid nanoarchitecture of two-dimensional molybdenum disulfide nanosheets anchored on directly grown one-dimensional carbon nanotubes for use as a counter electrode in dye-sensitized solar cells

Abstract

Two-dimensional (2D) molybdenum disulfide (MoS2) nanosheets were synthesized to anchor onto the surfaces of directly grown one-dimensional (1D) carbon nanotubes (CNTs) on fluorinated tin oxide (FTO) glass. This three-dimensional (3D) vertically aligned hybrid nanoarchitecture was used in Pt-free counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). The prepared 2D MoS2 nanosheets, with exposed layers, provided a great deal of edge-plane catalytically active sites for I3− reduction. The directly grown 1D CNTs provide an attractive template that offers a large surface area to promote the loading of 2D MoS2 nanosheets for enhancing electrochemical activity. The CNTs directly grown on the FTO substrate provided a high-speed pathway that promoted charge transport and transfer, resulting in a lower electron lifetime that increased the exchange current density and reduced the charge-transfer resistance. The DSSCs assembled with the 3D vertically aligned MoS2/CNT hybrid nanoarchitecture CE achieved a power conversion efficiency of 7.83%, 9.5% higher than that of a cell prepared with a Pt film CE (7.15%).