In situ growth of hierarchical NiS2 hollow microspheres as efficient counter electrode for dye-sensitized solar cell.

Hierarchical NiS2 hollow microspheres (HM-NiS2) were successfully in situ grown on FTO by a one-step hydrothermal method, and then tested as the counter electrode (CE) for dye-sensitized solar cell (DSSC) for the first time. The SEM images reveal that the hierarchical NiS2 microspheres were successfully grown on FTO substrate. It is worth noting that some of the shells are partially broken, which is advantageous for providing more electrolyte adsorptions and electrocatalytic active sites. The electrocatalytic ability and electrochemical properties of the HM-NiS2 were studied by cyclic voltammetry, electrochemical impedance spectroscopy and Tafel polarization. The power conversion efficiency of 7.84% is achieved for the DSSC based on HM-NiS2 CE, which is close to that of the DSSC using Pt CE (7.89%). The results indicate that the in situ fabricated HM-NiS2 CE may be a good candidate for high efficiency and low-cost DSSCs.