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

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, 2DTi3C2-MXenes were further instead of traditional Pt as counter electrodes (CEs) in triiodide reduction for dyesensitized 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 interstratification 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.