Nickel silicotungstate-decorated Pt photocathode as an efficient catalyst for triiodide reduction in dye-sensitized solar cells

A new type of polyoxometalate material, K6SiW11O39Ni(H2O)·xH2O (denoted as SiW11Ni), was successfully synthesized and introduced to a dye-sensitized solar cell (DSSC) with modified traditional Pt as a novel composite counter electrode. The new counter electrode showed superior electrochemical catalytic activity for the reduction of I3− to I− in analysis utilizing a Tafel-polarization curve, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The DSSC assembled with the SiW11Ni/Pt photocathode exhibited an enhanced performance (7.03%) under the standard AM 1.5G illumination compared to the DSSC with a pristine Pt photocathode (6.65%). Furthermore, the DSSC based on the SiW11Ni/Pt photocathode had an increased light-harvesting efficiency and was very stable. The results demonstrate that SiW11Ni/Pt is an alternative and highly efficient counter electrode for dye-sensitized solar cells. Moreover, the facile design strategy is promising for fabricating efficient and inexpensive composite counter electrode catalysts for DSSCs.