Question: if one of your dyes contains platinum (which is rare) will that not make the hydrogen produced fron the leaves expensive? and possibly run out like the fossil fuels are...

Stuart Archer answered on 19 Jun 2013:

That’s a really good question, one I get asked a lot!

Whilst platinum is very expensive, it’s not the rarest or most expensive metal that scientists are looking at for making artificial leaves (Iridium is twice as expensive for example!)

Platinum is a very useful metal for researchers looking at these kind of dyes as it’s very easy to make a lot of different molecules with platinum at their centre and control things such as their shape and the colour of light that they absorb. You also actually need very little of it – for an artificial life with an area of 1 square meter, you would only need about 10 billions of a gram of the dye to cover the entire surface. You need so little because you want a layer of dye on the surface that’s only 1 molecule thick!

We are trying to find cheaper and less rare metals (such as nickel or copper) which do the same thing, but they behave differently to a heavy metal like platinum so it’s much more of a challenge.