Question: what elements, compounds and chemicals are the artificial leaves made from?

Stuart Archer answered on 20 Jun 2013:

There are a lot of different chemicals that go into making an artificial leaf! There are three main parts:

– A dye that absorbs light and converts it into electrical energy that can be used to power chemical reactions.
– A ‘substrate’ (the material that you stick the dye to) that transports the electrical energy to the places where the chemical reaction takes place
– A ‘catalyst’ which uses the electrical energy to convert water into hydrogen and oxygen (What is the chemical formula for water?)

The dye is made up of a heavy metal atom at it’s centre (we use platinum metal, but others include metals such as ruthenium, iridium or even gold!) This is surrounded by an ‘organic’ molecule that helps it do it’s job (this is made up of various arrangements of carbon, hydrogen, nitrogen and oxygen)

The ‘substrate’ is made up of a mineral, in our case it’s called ‘titanium dioxide’ – which is a titanium atom with two oxygen atoms bonded to it. There is a whole branch of chemistry dedicated to working out which works best – there are atoms such as tin, chromium, gallium, germanium, indium, lead, bismoth, antimony…

The ‘catalyst’ is the least well understood part at the moment. The best ones that we have now are a chromium metal atom surrounded by another organic molecule. This is the biggest challenge we need to work out!