The Next Solar Powered Plant

PLANTS ARE MARVELOUSLY efficient solar-powered factories that convert carbon dioxide to cellulose. Chemical engineers have long wished they could adapt this process to synthesize other chemicals without burning fuel. Now, Mark E. Thompson, associate professor of chemistry at the University of Southern California, says he's taken the first step: the creation of a solar "chemophyll," modeled on chlorophyll in plants.

Though it converts sunlight to energy, Thompson's chemophyll bears little similarity to conventional solar cells. It consists of two thin layers of organic compounds on an ultrathin gold sheet. The inner layer functions as an electron donor and the outer as an acceptor. When light strikes the outer surface, electrons flow between the layers, establishing a current. Unlike silicon cells, the chemophyll works in electrolyte solutions conducive to chemical reactions.

The chemophyll produces less power than a typical silicon device. But with better materials, Thompson hopes to achieve higher voltages. This could lead to cells that act as catalysts to assist the conversion of COsubscript2 to methane, or to separate clean-burning hydrogen from oxygen in sea water.