Low-cost and novel preparation of porous NiS2/graphene heterojunctions photoanodes for high-efficiency dye-sensitized solar cells

Its critical and challenging to investigate cost-effective and strong electrocatalyst within the advancement of large scaled dye-sensitized solar cells (DSSCs). In this work, we develop a novel strategy to prepare NiS2 microspheres interface with 2D graphene nanosheets constructed through a facile hydrothermal technique. Na(2)S(2)O(3 center dot)5H(2)O plays an important role as the reducing agent for GO as well as the sulfur source for NiS2. The microstructures, morphologies and optical properties of the NiS2/graphene hybrid composite samples were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and N-2 adsorption-desorption isotherm, UV-Vis diffuse reflectance spectra and photoluminescence spectra analysis. A significant narrowing the band gap (2.69 eV-2.44 eV) and control the prevention of electron-hole pair recombination process was examined through UV and PL studies. The J-V characteristics of the fabricated sandwich type DSSC device was monitored and the results demonstrate that NiS2/graphene hybrid photoanode displayed an excellent electrocatalytic activity in the reduction of I-3(-) showing a power conversion efficiency of 12.56%, which is 2.5 times better than bare NiS2 photoanode (5.02%). This is ascribed to the low resistance to diffusion and transfer of electrolyte ions. These results suggest that the NiS2/graphene prepared through a facile process is a promising substitute to Pt electrode.