Photobioelectrochemical Cells Converted for Solar Collection

A fabrication method based on natural photosynthetic reactions could enable the conjugation of photobioelectrochemical cells to photobioelectrocatalytic solar cells.

The design of photobioelectrochemical cells based on native photosynthetic reactions has been investgated as a means for the conversion of solar light energy into electrical power. In natural systems, the photosynthetic reaction is coupled to biocatalytic transformations leading to CO₂ fixation and O₂ evolution. While progress has been achieved in the integration of native photosystems with electrodes for light-to-electrical energy conversion, the conjugation of the photosystems to enzymes to yield photobioelectrocatalytic solar cells remains a challenge.

Photobioelectrochemical cells point to a novel method to photonically drive biocatalytic fuel cells while generating electrical power from solar energy. Courtesy of Itamar Willner.

Now researchers from the Hebrew University of Jerusalem and the University of Bochum, Germany, have reported on the construction of photobioelectrochemical cells using the native photosynthetic reaction and the enzymes glucose oxidase or glucose dehydrogenase.

The system consisted of modified integrated electrodes that include the natural photosynthetic reaction center, known as photosystem I, conjugated to the enzymes. The native proteins were electrically wired by means of chemical electron transfer mediators.

Photoirradiation of the electrodes led to the generation of electrical power, while oxidizing the glucose substrate as a fuel.

The system provides a model to harness the native photosynthetic apparatus for the conversion of solar light energy into electrical power, using biomass substrates as fuels, the researchers said. In contrast to bioelectrochemical systems that use electrical power to oxidize glucose, the study implemented the native photosystem to produce electrical power using light as the energy source.

The researchers said the novel cells point to a new method to photonically drive biocatalytic fuel cells while generating electrical power from solar energy.

"The study results provide a general approach to assemble photobioelectrochemical solar cells with wide implications for solar energy conversion, bioelectrocatalysis and sensing,” said Hebrew University professor Itamar Willner.

The research was published in Nature Energy (doi: 10.1038/nenergy.2015.21).