Copper adorns Edinburgh’s Usher Hall, makes sturdy, affordable power cables and helps our bodies absorb iron. Now, researchers at Duke University in the US want to use Cu to transform sunlight and water into a chemical fuel.
Converting solar energy into storable fuel remains one of the greatest challenges of modern chemistry.
One way chemists have tried to capture the power of the sun is via water splitting, in which the atoms of H2O are broken apart so the hydrogen may be collected and used as fuel . . . electro-hydrolysis.
Plants do this through photosynthesis, and for half a century, scientists have tried to recreate that process by tinkering with chemical catalysts jump started by sunlight.
Indium tin oxide (ITO) is one material they’ve commonly tried to use. Researchers prefer it for its transparency – which allows sunlight to pass through and trigger the water-splitting reactions – and its ability to conduct electricity.
However, Duke’s team has created something it hopes can replace scarce ITO, namely copper nano-wires fused in a see-through film.
Cu is 1,000 times more plentiful and 100 times less expensive than indium. Cu nano-wire catalysts cost less to produce than the ITO equivalent as they can be “printed” on pieces of glass or plastic in a liquid ink form.
ITO production, by contrast, is slow and costly.
The nano-wires provide a high surface area for catalysing chemistry, and the team experimented with coating them in either cobalt or nickel – metals that serve as the actual chemical catalyst.
Even with a coat of cobalt or nickel, the nano-wire films allow nearly seven times more sunlight to pass through than ITO. The films are also flexible, leading the team to speculate that the completed fuel cells could one day even be attached to back-packs.