FeS2/FeCoS2 nanoparticles/reduced graphene oxide interfacial composite structure as highly reactive counter electrodes in dye-sensitized solar cells

In this article, the nanoparticles of CoFe2O4 and FeS2/FeCoS2 have been generated by direct oxidation and sulfurization of Fe-Co precursor and used as counter electrode (CE) material for dye-sensitized solar cells (DSSCs). Compared with CoFe2O4, FeS2/FeCoS2 nanoparticles have superior electrical conductivity and catalytic activity. Furthermore, the introduction of reduced graphene oxide (RGO) improved the performance of FeS2/FeCoS2. By attaching FeS2/FeCoS2 nanoparticles to the surface of RGO, it alleviated the agglomeration of nanoparticles effectively. Meanwhile, the catalytic activity and electrical conductivity of FeS2/FeCoS2@RGO in DSSC are greatly improved. With increasing contact area, the penetration rate of the electrolyte is accelerated, which results in a faster reaction rate of tri-iodide that can be significantly accelerated. We explain the modification of FeS2/FeCoS2 nanoparticles by RGO through the morphology characterization and electrochemical performance test. The DSSCs assembled by FeS2/FeCoS2@RGO achieved a choiceness power conversion efficiency (PCE) of 7.84%, which is higher than those of CoFe2O4 nanoparticles (3.71%), FeS2/FeCoS2 nanoparticles (7.05%), and platinum (Pt) (7.54%).