Fig. 4From: Efficient Nickel Sulfide and Graphene Counter Electrodes Decorated with Silver Nanoparticles and Application in Dye-Sensitized Solar CellsEquivalent circuits used for simulating the obtained EIS results (a). Nyquist plots of the symmetrical Pt, Gr, NiS, NiS/Gr, NiS/Ag, and NiS/Gr-Ag CEs for I −/I 3 − redox couple (b)Back to article page