Brick Shaped Vanadium Nitride/Graphene Nanocomposite as Highly Efficient Counter Electrode Catalyst for Pt Free Dye-Sensitized Solar Cell

A Platinum free hybrid counter electrode (CE) Vanadium nitride/graphene (VNGp) for dye-sensitized solar cell (DSSC) was synthesized by hydrothermal method. The surface morphology and chemical composition of the as-prepared VNGp composite were analyzed by X-ray diffraction (XRD) analysis, Raman spectroscopy, high-resolution electron transmission microscopy (HR-TEM), and cyclic voltammetry (CV). The VNGp hybrid counter electrode displayed an adsorption-controlled process towards the (I-/I-3(-)) redox couple at CE/electrolyte interface and the value was calculated to be 3.16x10(-9) mol/s by varying the scan rate. The exchange current density (J(o)) was calculated as 6.59 mA/cm(2) from the Tafel slope. The VNGp hybrid counter shows a maximum fill factor (FF) of 66.28 with high efficacy of 8.15 % under the illumination of 100 mW/cm(2) as compared to the Pt CE for DSSC.