First step to converting solar energy using 'artifi...( An international team of researchers...)

An international team of researchers has modified chlorophyll from an alga so that it resembles the extremely efficient light antennae of bacteria. The team was then able to determine the structure of these light antennae. This is the first step to converting sunlight into energy using an artificial leaf. The researchers will be publishing an article on their research findings in the online Early Edition of the PNAS journal in the week starting 29 June. Leiden researcher Swapna Ganapathy has obtained her PhD based on this subject, under the supervision of Professor Huub de Groot, one of the initiators of the research.

Forests at nano scale

They are the subject of dreams: artificial forests at nano scale. Or pavements and motorways where gaps in the surface are filled with pigment molecules that collect sunlight and convert it into fuel and other forms of clean energy. But before this can happen, artificial photosynthesis systems first have to be developed that work both quickly and efficiently.

Two things are needed to generate fuel from sunlight: an antenna that harvests light, and a light-driven catalyst. The article in PNAS is about the first of these: the antenna.

Imitating light antennae of bacteria

The fastest light harvesters are to be found in nature: in green leaves, algae and bacteria. The light antennae of bacteria chlorosomes are the fastest of all. They have to be capable of harvesting minimal quantities of light particles in highly unfavourable light conditions, such as deep in the sea. These chlorosomes are made up of chlorophyll molecules. The art is to imitate these systems very precisely.

German colleagues from the University of Wrzburg in Huub de Groot's team modified chlorophylls from the alga Spirulina, such that they resembled the pigments of bacteria. De Groot's Leiden group then studied the structure of these semi-synthetic light antennae.