Effects of Carbon Allotrope Interface on the Photoactivity of Rutile One-Dimensional (1D) TiO2 Coated with Anatase TiO2 and Sensitized with CdS Nanocrystals

The assembly of a large-bandgap one-dimensional (1D) oxide-conductive carbon-chalcogenide nanocomposite and its surface, optical, and photoelectrochemical properties are presented. Microscopy, surface analysis, and optical spectroscopy results are reported to provide insights into the assembly of the nanostructure. We have investigated (i) how the various carbon allotropes (C60), reduced graphene oxide (RGO), carbon nanotubes (CNTs), and graphene quantum dots (GQDs) can be integrated at the interface of the 1D TiO2 and zero-dimensional (0D) CdS nanocrystals; (ii) the carbon allotrope and CdS loading effects; (iii) the impact of the carbon allotrope presence on 0D CdS nanocrystals; and (iv) how they promote light absorbance. Subsequently, the functioning of the integrated nanostructured assembly in a photoelectrochemical cell has been systematically investigated. These studies include (i) chronoamperometry, (ii) impedance measurements or EIS, and (iii) linear sweep voltammetry. The results indicate that the presence of a GQD interface shows the most enhancement in the photoelectrochemical properties. The optimized photocurrent values were respectively noted to be 2.8, 2.2, 1.9, and 1.6 mA/cm(2), indicating JGQD > JRGO > JCNT > Jfullerene. Furthermore, the annealing conditions have indicated that ammonia treatment leads to an increase in the photoelectrochemical responses when using any form of the carbon allotropes.