Artificial leaf mimics photosynthesis to make fuel from water

Los Angeles: Researchers have successfully developed an artificial leaf which mimics the process of photosynthesis to create fuel using water, carbon dioxide and sunlight.The new system consists of three main components: two electrodes - one photoanode and one photocathode - and a membrane.

The photoanode uses sunlight to oxidise water molecules, generating protons and electrons as well as oxygen gas. The photocathode recombines the protons and electrons to form hydrogen gas. A key part of the design is the plastic membrane, which keeps the oxygen and hydrogen gases separate.

If the two gases are allowed to mix and are accidentally ignited, an explosion can occur; the membrane lets the hydrogen fuel be separately collected under pressure and safely pushed into a pipeline. Semiconductors such as silicon or gallium arsenide absorb light efficiently and are therefore used in solar panels.

However, these materials also oxidise (or rust) on the surface when exposed to water, so cannot be used to directly generate fuel. The new complete solar fuel generation system developed by Nate Lewis, professor at California Institute of Technology, and colleagues uses a 62.5-nanometre-thick titanium dioxide (TiO2) layer to effectively prevent corrosion and improve the stability of a gallium arsenide-based photoelectrode. Another key advance is the use of active, inexpensive catalysts for fuel production.