Fabrication of Carbon/Zinc Oxide Nanocomposites as Highly Efficient Catalytic Materials for Application in Dye-Sensitized Solar Cells

Abstract

Different nanostructured semiconducting ZnO photoanodes were prepared by Hydrothermal (HT), Co-precipitation (CoP) and Chemical Bath Deposition (CBD) methods for their use in the Dye Sensitized Solar Cells (DSSCs) in the present study. Additionally, different ZnO nanocomposites were synthesized by mixing the Carbon Nanotubes (CNTs), Graphene Oxide (GO) and their combination with the ZnO nanostructures. Scanning electron microscopy (SEM) revealed various morphologies of ZnO nanostructures and nanocomposites such as nanoflowers, nanorods, rhombohedral, cubic, and cauliflower-like nanorods, and nanorods with hexagonal symmetry. Energy Dispersive X-ray (EDX) spectra confirmed the purity of the synthesized samples. X-ray Diffraction (XRD) demonstrated the hexagonal wurtzite phase of ZnO and a minor presence of CNTs and graphene. The UV-Visible, transmittance and diffuse reflectance spectra demonstrated that the ZnO synthesized through the CBD method exhibits the highest transmittance as 70–71% in the UV-Vis range and reduced % R. Optical band gaps of the samples were determined with the help of Tauc plots. Comparison of J-V characteristics showed that the ZnO synthesized via the HT method exhibits the highest conversion efficiency of 1.45%. Comparison among pristine ZnO synthesized via CBD and ZnO nanocomposites revealed that ZnO/CNTs possesses the highest energy conversion efficiency of 1.23% with enhanced JSC of 4.49 mA/cm2.