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. The photocathode recombines the protons and electrons to form hydrogen gas.
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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.
The new 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.
“The device grew out of a multi-year, large-scale effort to define the design and material components needed for an integrated solar fuel generator,” said Harry Atwater, director of Joint Centre for Artificial Photosynthesis (JCAP) and Howard Hughes, professor of Applied Physics and Materials Science at Caltech.
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The photoanode was grown onto a photocathode, which contains a highly active, inexpensive, nickel-molybdenum catalyst to create a fully integrated single material that serves as a complete solar-driven water-splitting system.