Novel 2D heterostructure composites of V2C MXene/TiO2 and graphene/ TiO2 for platinum replacement in dye-sensitized solar cells

This study evaluates the potential of V2C MXene/TiO2 and Graphene/TiO composites as alternatives to platinum for counter-electrodes in dye-sensitized solar cells (DSSCs). V2C MXene was synthesized by selectively etching the aluminum layer from V2AlC MAX phase powder, resulting in multilayered V2C MXene. The layered morphologies of MXene and graphene were confirmed via Scanning Electron Microscopy (SEM), while their crystalline structures were validated using X-ray diffraction (XRD) analysis. SEM analysis confirmed the delaminated layered structure of graphene and the distinct layers of V2C MXene. XRD findings showed that MXene has significantly greater interlayer spacing than graphene, offering more catalytic sites for charge injection. Electrocatalysts were prepared by incorporating TiO2 paste with MXene and graphene, with TiO2 serving as a binder. These composites were then employed as counter-electrode materials in dye-sensitized solar cells. The MXenebased counter electrode achieved a photoconversion efficiency of 1.625 %, surpassing graphene-based (1.149 %) and Pt-based (1.567 %) counterparts under standard illumination. The efficiency of cells was meticulously characterized over an extended period. The results indicated that the efficiency of these cells remained stable over time. This stability suggests that MXene/TiO2 and Graphene/TiO2 based catalysts are robust and do not degrade with time.