Photoelectrochemical water splitting properties of CdS/TiO2 nanofibers-based photoanode

Abstract

CdS-sensitized TiO2 nanofibers (CdS/TiO2 NFs) structures were fabricated on the indium tin oxide (ITO) conducting substrate that acts as a working electrode in photoelectrochemical (PEC) cell for the generation of hydrogen by water splitting. TiO2 NFs on ITO conducting substrate were synthesized by electrospinning technique using Titanium tetraisopropoxide as the precursor, followed by a calcination process in air at 500 °C for 2 h. CdS deposition on TiO2 NFs structures was carried out by the dip coating method with different dipping times to optimize the water splitting efficiency. The morphologies and crystalline structures of fabricated samples were characterized by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The PEC properties of the electrodes were measured using a potentiostat instrument in a mixture of 0.25 M Na2S and 0.35 M Na2SO3 aqueous solutions for CdS/TiO2 photoanodes and in 0.5 M Na2SO4 electrolyte for uncoated TiO2 photoanode under the illumination of simulated sunlight (100 mW/cm2 from 150 W xenon lamp). It was found that an optimized TiO2 NFs structure sensitized by CdS layer yields a photoconversion efficiency of 3.2% at 0.0 V (vs. Ag/AgCl). The value of photocurrent density for CdS/TiO2 NFs samples were more than 20 times higher than that of the uncoated TiO2 NFs sample at 0.0 V (vs. Ag/AgCl) under a simulated sunlight irradiation.