Enhanced catalytic properties of bimetallic sulfides with the assistance of graphene oxide for accelerating triiodide reduction in dye-sensitized solar cells

High cost of Pt counter electrode restricts large-scale application of dye-sensitized solar cells (DSSCs). Therefore, it is of great practical significance to develop new counter electrode materials with low cost, good stability and high catalytic activity to replace Pt counter electrode. In this paper, bimetallic sulfides (Co8FeS8/N-C and (Co0.75Ni0.25)(9)S-8/N-C anchored on graphene oxide (GO) were synthesized using ZIF-67 as precursor by subsequent sulfuration and cation exchange method. The electrochemical results showed that the composite of Co8FeS8/N-C/GO and (Co0.75Ni0.25)(9)S-8/N-C/GO displayed improved electrocatalytic performance for I-/I-3(-) redox reaction owing to the introduction of GO and the synergic catalytic effect between bimetallic sulfides and GO. When Co8FeS8/N-C/GO and (Co0.75Ni0.25)(9)S-8/N-C/GO were applied as low-cost counter electrode for the DSSCs, they achieved high photo-electric conversion efficiency of 8.74% and 8.98%, respectively. This notion and expedient strategy of combination could be widened to construct other composite of bimetallic sulfides with GO, which might exhibit the desired electrocatalytic performance and potential applications.