High Catalytic Activity of W18 O49 Nanowire-Reduced Graphite Oxide Composite Counter Electrode for Dye-Sensitized Solar Cells

Abstract

The W18O49 nanowire (NW)-reduced graphite oxide (W18O49-rGO) nanocomposite was prepared by a facile solvothermal reaction. The W18O49 NWs were stably dispersed on the surface of rGO, and the content of W18O49 NWs in the composite can be tailored by controlling the mass ratio of reactants (WCl6 and graphite oxide). Employing the W18O49-rGO nanocomposite with the proper W18O49 NW content of 33% as a counter electrode of dye-sensitized solar cells (DSSCs), it gets a photoelectrical conversion efficiency (η) of 7.23%, which is close to that of Pt-based DSSC (7.39%). The high efficiency of DSSCs based on W18O49-rGO counter electrode is contributed to the intrinsic electrocatalytic activity of W18O49 NWs and excellent electron-transfer characteristics of rGO. The first-principles calculations have been first employed to investigate the adsorption energy between I3− molecule and W18O49 NW to explain its good catalytic activity. The cyclic voltammetry (CV), electrochemical impedance spectra (EIS), and Tafel polarization tests can further identify that the W18O49-rGO counter electrode has high electrocatalytic activity for the reduction of I3− and low interface charge transfer impedance. It is believed that the W18O49-rGO nanocomposite can be used as a promising counter electrode material for DSSCs.