General Status and Prognosis for Photoelectrosynthesis

General Status and Prognosis for Photoelectrosynthesis. The photoelectrosynthetic approach to solar energy conversion is very appealing and exciting and deserves continued intense attention. 

The potential advantages of photoelectrosynthesis over photovol-taics coupled to dark electrosynthesis are in higher net conversion efficiency, better engineering designs for solar reactors, and unique catalytic effects possible with modified semiconductor electrode surfaces. 

The main problem in the field is the lack of semiconductor materials that exhibit high conversion efficiency and long term stability. However, one very promising approach involves the chemical modification or derivatization of the semiconductor surface to enhance photo-stability and catalytic activity. This approach is interesting in that it represents a common intersection with the current directions of photochemical approaches to solar energy conversion (61). In the latter, systems are being studied that involve semiconductor particles as catalysts to help drive the photochemical redox reactions. These semiconductors act as electron pools to facilitate the redox chemistry and catalyze the desired reactions. 

It appears that the optimum system may involve semiconductors (to absorb, the light and separate the photo-induced charge carriers), in the form of fine particles (for optimum engineering design), but modified on the surface with chemical compounds (to enhance stability, catalytic activity, and perhaps also optical absorptivity). 

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