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

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.