Step by Step Water Splitting: Heterogeneous Photocatalysis Studies

Abstract

Due to the environmental problems caused by the steadily increasing usage of fossil fuels, the interest for renewable sources of energy has amplified significantly. Among the several possibilities, hydrogen gas is considered to be one of the most promising fuels forof the future. IfOnce formed from water via photocatalysis it is a desirable, convenient and green improvement in the field of energy. During this work, we have tried to contribute to this important field.

4wt.% Au/TiO2 synthesized by deposition-precipitation with urea was the main photocatalysts used in this project. Other noble metal-loaded (Pt and Ag) titanium dioxide materials were synthesized by deposition precipitation with urea and other methods such as sol gel and sol immobilization. These catalytic systems were studied and their activity compared for hydrogen production from water/methanol mixtures. Sets of monometallic Au, Ag, Pt and bimetallic Au-Pt and Au-Ag supported titanium dioxide were synthesized and tested.

Au/TiO2 photocatalysts synthesized by deposition precipitation with urea was were the best in terms of hydrogen production compared to other photocatalysts. In the evaluation of possible sacrificial molecules, isopropanol was less efficient than methanol. Through the formation of bi-metallic Ag-Au/TiO2 and Pt-Au/TiO2 catalysts, the hydrogen production could be further improved. Finally, Ir supported Al2O3 was investigated for the first time as a heterogeneous catalyst for hydrogen production by photocatalytic dehydrogenation of aqueous p-formaldehyde and photoreduction of carbon dioxide.