Solar Light-Responsive Pt/CdS/TiO2 Photocatalysts for Hydrogen Production and Simultaneous Degradation of Inorganic or Organic Sacrificial Agents in Wastewater

Photocatalytic degradation of waste material in aqueous solutions and simultaneous production of hydrogen was studied with the double purpose of environmental remediation and renewable energy production. Both powdered and immobilized Pt/CdS/TiO2 photocatalysts were used to oxidize model inorganic (S-2/SO32-) and organic (ethanol) sacrificial agents/pollutants in water. Powdered Pt/CdS/TiO2 photocatalysts of variable CdS content (0-100%) were synthesized by precipitation of CdS nanoparticles on TiO2 (Degussa P25) followed by deposition of Pt (0.5 wt %) and were characterized with BET, XRD, and DRS. Immobilized photocatalysts were deposited either on plain glass slides or on transparent conductive fluorine-doped SnO2 electrodes. The results show that it is possible to produce hydrogen efficiently (20% quantum efficiency at 470 nm) by using simulated solar light and by photocatalytically consuming either inorganic or organic substances. CdS-rich photocatalysts are more efficient for the photodegradation of inorganics, while TiO2-rich materials are more effective for the photodegradation of organic substances.