Harnessing light energy by mimicking photosynthesis could be the future for energy systems.
29 November 2006
Harnessing light energy by mimicking photosynthesis could be the future for energy systems, say Japanese scientists.
Shigeru Murata and colleagues from the University of Tokyo claim to have created the closest model of photosynthesis to date. They hope the model will help in developing artificial systems for converting solar energy into chemical potential energy.
Harnessing light energy by mimicking photosynthesis could be the future for energy systems.
Naturally, plants extract energy from sunlight to produce carbohydrates from carbon dioxide and water. To do this, chlorophyll, a substance present only in plants and other photosynthetic organisms, releases an electron when activated by sunlight. The electron travels through a photosynthetic membrane in the cell, to react with the oxidised form of a compound called nicotinamide adenine dinucleotide phosphate (NADP). This produces NADPH, which reduces carbon dioxide to carbohydrates.
Using mimics of the photosynthetic membranes, Murata's team demonstrated that electron transport across the membranes could be driven by irradiating aromatic hydrocarbons, called pyrenes, embedded within them. Studying this process in greater detail, the group designed and synthesised novel pyrenes, which improved the electron transport efficiency.
Although the model does not work with visible light, it does satisfy most of the criteria needed to resemble natural photosynthesis. Murata suggested that the electron transport system should be linked with a reductive catalytic reaction, such as hydrogen production from water or carbon dioxide conversion into methanol or methane. All of these products can be oxidised to give us energy, said Murata, although choosing the electron donor to prepare them will be particularly challenging.
Elinor Richards
Pyrene-sensitized electron transport across vesicle bilayers: dependence of transport efficiency on pyrene substituents T Mizushima, A Yoshida, A Harada, Y Yoneda, T Minatani and S Murata, Org. Biomol. Chem., 2006, 4, 4336.