Solar energy converters, artificial

Much has been written about artifical solar-energy converters - the reader is referred to references 10, 12, 14-17 for detailed treatments. Here I shall deal exclusively with those artificial systems designed to mimic various aspects of the photosynthesis reaction. 

The electrons that are provided by photosystem I are finally used to reduce CO2 to carbohydrates, while in photosystem II, water is oxidized to oxygen. Intense research over many decades has partially revealed the extremely complicated mechanism of natural photosynthesis. It follows that it is obviously rather difficult to imitate this in an artificial photosynthesis that is intended to convert and store solar energy in simple but energy-rich chemicals. Different approaches have been developed to solve this problem (i). It has been suggested to facilitate artificial photosynthesis by the assistance of redoxactive metal complexes in homogeneous systems. Generally, photoredox reactions of metal... 

On the other hand, single-wall CNTs (SWCNTs) can efficiently absorb and convert photon energy into thermal energy and have excellent thermal conductivities. Thus, they can act as a nanoscale heat source and thermal conduction pathway to heat the crosslinked LCP matrix effectively [51]. Furthermore, the resultant crosslinked PLCP/SWCNT nanocomposites exhibited effective photoactuation not only by white light but by near-IR irradiation as well [52]. Such nanocomposites were used to direct sun-driven artificial heliotropism for solar energy harvesting [53]. 

Biofuel industry is one of the upcoming industries who are in search of new and different strategies for the conversion of biomass into biofuel products. Since Archaea are exposed to strict sunlight, they have adapted a mechanism to convert solar energy by the transversion of protons and chloride ions for phototaxis. They harbor light sensitive proteins called the bacterial rhodopsin, a 25 kDa protein that carries the retinal group linked to lysine-216 by the Schififbase action. The bacteriorhodopsin protein is used in holography, spatial modulators, artificial retina and volumetric and associative optical memories (Alqueres et al., 2007). 

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