Laminated 2D-Ti3C2-MXenes as high-performance counter electrode for triiodide reduction in dye-sensitized solar cells

Abstract

The different surface terminals, sizes, and sheet quality of laminated 2D-Ti3C2-MXenes were prepared by selective etching intermediate Al atoms layer form the strongly bonded compound Ti3AlC2 as precursor at low temperature using different etchants of HF, HF + HCl, LiF + HCl, and NH4HF2 for 24 h, respectively. Then, 2D-Ti3C2-MXenes were further instead of traditional Pt as counter electrodes (CEs) in triiodide reduction for dye-sensitized solar cells (DSSCs). The selection of different etchant directly affects the properties and performance of the laminated 2D-Ti3C2-MXenes catalyst. Herein, the DSSCs with 2D-Ti3C2-MXenes CEs yielded power conversion efficiencies (PCE) of 7.15 % (HF-), 6.06 % (HF + HCl-), 6.38 % (LiF + HCl-), and 6.05 % (NH4HF2-) for regenerate traditional I3−/I− shuttles via the photocurrent-voltage (J-V) test, respectively. The outstanding electrocatalytic performances of laminated 2D-Ti3C2-MXenes can be attributed to the formation of regular inter-stratification structures by etching to expose larger specific surface areas and further generate more catalytic reaction sites, as well as the acceleration of I3−/I− shuttle diffusion channels by adjusting the interlayer d-spacing, implying a potentially candidate of Pt catalyst for applications in the encapsulated DSSCs as Pt-free CEs.