Hollow spherical NiS/NiS2 composite as effective counter electrode catalyst for dye-sensitized solar cells

Abstract

In this study, NiS/NiS2 composite hollow spheres were synthesized by a one-step solvothermal route without the help of template or surfactant. Electrochemical behavior of NiS/NiS2 composite was investigated through the cyclic voltammetry, electrochemical impedance spectroscopy and Tafel polarization tests. The results exhibit that the NiS/NiS2 composite possess excellent electrocatalytic activity toward the reduction of I3−, superior electrochemical stability and low charge transfer resistance (0.34 Ω cm−2) at the electrode/electrolyte interface. When used as counter electrode (CE) catalyst for dye-sensitized solar cells, hollow spherical NiS/NiS2 composite achieved a satisfactory power conversion efficiency of 7.66 %, which outperformed that of using Pt CE (7.01 %).