(177c) Solar Energy Driven Catalytic Reduction of Carbon Dioxide in the Gas Phase
Solar energy driven reduction of carbon dioxide in the gas phase is a natural phenomenon known as photosynthesis. As with many other natural processes, the simple process building blocks are combined in perfect complexity yielding marvelous outcomes. The objective of this talk is to present the efforts on understanding natural photosynthesis, and imitate it as what can be called artificial photosynthesis or photocatalytic redox reactions. The simplest scheme of photocatalysis consists of (i) the absorption of electromagnetic radiation by a semiconductor with an appropriate gap between the valance and the conduction bands in order to generate charge carriers in terms of electron-hole pairs; (ii) capturing these charge carriers at the catalytically active sites to initiate redox reactions; (iii) Completing the reaction scheme with thermally driven steps to produce the reduction products and oxygen. The ?magic powder? or ?magic film? to perform all of these must possess the semiconductor properties to absorb light at the correct wavelength, the catalytic activity to drive the reactions at acceptable pace, along with the salient features as to be stable, non toxic and readily available. Since it is not possible to have one single material with all of these features, the skills of a Chemical Engineer to design a process must be translated into the skills to design the product with the desired properties. In this talk, the limited understanding about photosynthesis translated into the photocatalytic processes will be reviewed. The state of the art of the ?storage of the solar energy in chemical bonds? in our group and in the groups around the world will be presented.