CO2 Sequestration and Recycle by Photosynthesis

Abstract

Hydrocarbon synthesis from photocatalytic reactions of CO 2 and H 2 O over various catalysts has been studied by UV-visible light. The quantum efficiencies suggest that Pd/TiO 2 sol gel exhibits the highest activity for hydrocarbon synthesis from photocatalytic reactions. The in situ IR was able to monitor the adsorbed hydrocarbon species. The UV-visible, IR spectroscopy and XRD techniques were used to characterize the catalysts to obtain the information of properties of the process and catalyst before/after reaction. The UV-visible spectroscopy provides the information about the surface band gap energy of each catalyst. In situ UV-visible studies reveals that TiO 2 -supported catalysts require the higher energy (i.e.shorter wavelength) to pass through the water-thin film deposited on the surface to activate the photocatalytic reaction. XRD data show there is changes in the crystal structure of TiO 2 sol gel from photon energy during photo reaction. Studies on photocatalytic oxidation of methylene blue show that the photocatalytic oxidation rate is significantly higher than the photocatalytic reduction rate on TiO 2 based catalysts. The information from this study can lead to a better understanding of the nature of the catalysts and photoreaction processes, which might provide the information to develop better catalysts and reaction process for the hydrocarbon synthesis from photocatalytic reactions of CO 2 and H 2 O.3