Preparation of high efficiency visible light activated Pt/CdS photocatalyst for solar hydrogen production

Abstract

Production of hydrogen by water splitting using solar energy is one of the long sought goals of hydrogen economy. Approximately 33% of solar radiation is emitted as high energy photons while the remaining 67% consists of primarily thermal energy. Utilization of both thermal and photonic energies within the solar spectrum is essential for achieving water splitting at high efficiency. At FSEC, we have developed a solar-thermochemical water splitting cycle for the production of hydrogen. In this cycle, the photonic portion of solar irradiance is diverted and used to drive the hydrogen production step, while solar thermal portion drives the oxygen generation step of the cycle. The photocatalytic hydrogen production step of the cycle employs aqueous ammonium sulfite solution that is oxidized to ammonium sulfate in the presence of nanosized photocatalysts. We have developed a technique for the preparation of polymer encapsulated nanosize photocatalysts that show high activity toward oxidation of ammonium sulfite aqueous solution. The use of nano-scale and defect free photocatalysts hinder the recombination of photo-generated electron-hole pairs, thereby increasing solar to hydrogen energy conversion efficiency.