Ni–Fe–WSx polynary hollow nanoboxes as promising electrode catalysts for high-efficiency triiodide reduction in dye-sensitized solar cells

Abstract

Hollow functional materials with adjustable morphologies based on transition metal sulfides have been considered as a class of attractive and promising electrocatalysts for multifarious energy conversion devices. Herein, we adopt a facile template-engaged method to synthesize morphology-tunable Ni–Fe–WSx hollow nanoboxes by changing the mass ratios (1/1, 1/2 and 1/3) of nickel iron Prussian-blue analog precursors and (NH4)2WS4. During the above processes, (NH4)2WS4 acted as a multifunctional vulcanizator to supply elements of S and W simultaneously and the surface of Ni–Fe–WSx nanoboxes became rougher with the increment of WS42−. Noteworthy, profiting to the moderated surface morphology, appropriate doped ratio and the synergistic effect of multiple elements, Ni–Fe–WSx-2 hollow nanoboxes not only possessed higher specific surface and well-defined interior voids but also performed excellent catalytic properties on promoting the reduction of I3− comparing to Ni–Fe–WSx-1, Ni–Fe–WSx-3 and Ni–Fe–S in dye-sensitized solar cells (DSSCs). As expected, the DSSC prepared with a Ni–Fe–WSx-2 counter electrode (CE) possessed a higher value of power conversion efficiency (PCE) about 9.86% which was more remarkable than that of Pt (8.20%).