Synthesis of ruthenium sulfide nanoparticles decorated on reduced graphene oxide/multi-walled carbon nanotubes as a catalytic counter electrode for dye-sensitized solar cells exceeding 13 % efficiency

The luxury price, shortage, and instability of platinum (Pt) markedly hamper its commercialization in dye-sensitized solar cells (DSSCs). Consequently, developing an efficient alternative catalyst in lieu of noble Pt is imperative issue for the promotion of DSSCs. In this paper, a robust and electrochemically stable 3D nanocomposite comprised of amorphous ruthenium sulfide nanoparticles (RuS2 NPs), reduced graphene oxide (RGO), and functionalized multi-walled carbon nanotubes (MWCNTs) was prepared by the facile hydrothermal method and explored as a counter electrode (CE) in DSSCs. The RuS2 NPs uniformly decorated on the surfaces of the RGO/MWCNTs to form the RuS2/RGO/MWCNTs composite, which adequately inhibited aggregation of the RuS2 NPs to fully exploit its impressive electrochemical activity. Benefiting from the unexceptionable catalytic activity of RuS2 NPs in the RuS2/RGO/MWCNTs as well as superior electronic transmission channels provided by the conductive RGO/MWCNTs network, the designed DSSC with RuS2/RGO/MWCNTs exhibited a remarkable power conversion efficiency (PCE) of 13.24 % exceeding that of Pt CE (PCE: 9.53 %). Consequently, this research opens a new avenue to fabricate advanced cathode catalysts based on metallic sulfides and carbon-based materials with excellent performance for their potential application in next-generation energy storage and conversion devices such as DSSCs, water splitting, and other electrochemical applications.