Green Hydrogen Production in an Optofluidic Planar Microreactor via Photocatalytic Water Splitting under Visible/Simulated Sunlight Irradiation
Laxmi Prasad Rao Pala, Nageswara Rao Peela
Abstract
The visible light-active Pt/TiO2 photocatalyst thin films were prepared by photo-depositing Pt onto the sol–gel TiO2 spin-coated films. An optofluidic planar microreactor was fabricated using a Pt/TiO2 film-coated glass substrate as the bottom plate and an uncoated glass substrate containing a planar reaction chamber as the cover plate. The Pt/TiO2 thin films were tested for the photocatalytic water splitting activity in the presence of methanol as the sacrificial agent to produce hydrogen under visible/solar light irradiation. The effect of catalyst film thickness, reactant flow rate, light intensity, and type of light source on the rate of hydrogen production was studied. The Pt/TiO2 film with a thickness of 1650 ± 119 nm showed a highest rate of 16.35 mmol h–1 g–1 (4.7 μmol h–1 cm–2) hydrogen production at an optimum reactant flow rate of 0.3 mL min–1 under visible light (400 W metal halide lamp) irradiation. The stability study carried out for four cycles of 5 h runs proved that the photocatalyst was stable and the film was well adhered to the glass substrate. A hydrogen production rate of 0.766 mmol h–1 g–1 (0.22 μmol h–1 cm–2) and a solar to hydrogen conversion efficiency of 0.015% were obtained under a simulated solar light irradiation of ∼100 mW cm–2 intensity, proving the solar light activity of the Pt/TiO2 film.