Scientists take step towards artificial leaves

Developed by a team at Caltech’s Joint Center for Artificial Photosynthesis, the conductive nickel oxide film could, it is claimed, be applied to semiconducting materials to form so-called “artificial leaves” that replicate the natural process of photosynthesis used by plants.

The device  - which is the subject of a study in the Proceedings of the National Academy of Sciences - consists of three main components: two electrodes (a photoanode and a photocathode) and a membrane.

The photoanode uses sunlight to oxidise water molecules to generate oxygen gas, protons, and electrons, while the photocathode recombines the protons and electrons to form hydrogen gas. The membrane, which is typically made of plastic, keeps the two gases separate in order to eliminate any possibility of an explosion, and lets the gas be collected under pressure to safely push it into a pipeline.

According to Prof Nate Lewis, who has been heading up the research, the team experimented with a number of different light-absorbing semiconductor materials such as silicon or gallium arsenide (which are already used in solar panels) but found that they developed an oxide layer when exposed to water.