Synthesis of titania wrapped cadmium sulfide nanorods for photocatalytic hydrogen generation

Highlights: • TiO₂@CdS nanorods with core/shell morphology prepared by simple hydrothermal method. • TiO₂ shell thickness optimized for enhanced photocatalytic activity. • Initial concentration of sacrificial agent and solution pH were optimized for H₂ generation. • Optimized photocatalyst C₃T₃ displayed stable and continuous H₂ evolution for 20 h. • Optimised catalyst showed 12-folds efficient H₂ production under UV–vis vs visible light. - Abstract: Herein we report a simplified synthetic approach for a semiconductor photocatalyst (CdS) wrapped with a nanoscale thin-layer of semiconducting material (TiO₂) to overcome the instability issues, besides the improved catalytic efficiency. Images of HR-TEM and elemental mapping evidenced the presence of CdS that covered by ultra thin-layer of TiO₂ as shell. The UV–vis diffuse reflectance spectra showed red-shift in absorption edge in visible region. The photocatalytic water splitting towards hydrogen production using Na₂S/Na₂SO₄ as sacrificial agent was evaluated under UV–vis and visible light irradiation. The essential variables such as thickness of TiO₂ shell, amount of sacrificial agent and solution pH were fine tuned to achieve hydrogen generation of 5791 mL h⁻¹ g⁻¹ of catalyst. The higher efficiency is ascribed to core/shell morphology of CdS/TiO₂ system that channelled the excitons to the surface for the red-ox reactions rather than recombination. The catalytic stability result ascertained that the photo-corrosion is greatly suppressed.