Putting sunshine in the tank – using nanotechnology to make solar fuel.
Luminescence from solutions of small semiconductor clusters (‘quantum dots’) of different sizes. By simply changing the size of the dots, we can change the colour of light they absorb or give out – so we can match the dots to the part of the solar spectrum we want to collect. (credit: Nanoco Technologies Ltd).
Our Sun provides far more energy than we will ever need, but we use it very inefficiently. To do better, we must answer the question ‘what happens at night?’, when we can’t produce power from solar panels.
This exhibit shows how scientists are working to use the Sun’s energy directly; not to generate power, but make fuel – often called ‘solar fuel’. To make better use of the Sun’s resources, we need to find out how to create solar fuel that can be stored, shipped to where it is needed and used on demand. Weight-for-weight, fuel can store much more energy than batteries. Scientists are using nanotechnology to harness sunlight to drive green chemical reactions.
How does it work?
We use powerful lasers to mimick different sunlight colours in our lab. This is a high power laser system that creates very short light pulses in operation in the Photon Science Institute at the University of Manchester (credit: The Photon Science Institute, The University of Manchester).
The scientists behind this exhibit are working to build a solar ‘nanocell’ that will use the Sun’s energy directly to make important fuels or chemicals needed by industry. At the heart of the nanocell are two types of light-absorber – small semiconductor clusters called ‘quantum dots’, containing only a few hundred atoms, and porphyrin molecules (like those involved in photosynthesis).
In this fantastic quantum world, scientists can select which colour of sunlight is absorbed just by changing the size of the quantum dots. Catalyst molecules are grafted onto the surfaces of the dots, and these do the chemistry. When sunlight is absorbed, carriers of electric current are created (just as in a solar panel), but here they provide the potential to do useful chemistry with the catalyst – for example turning water into hydrogen fuel. This could be a green way of making the fuel for hydrogen-powered cars – instead of making it from fossil fuel as we do right now.
This short video introduces some of the work to be presented by this exhibit (2 mins).
Ask the scientists
Before the exhibition, visitors were invited to post questions about the science behind this exhibit. The comments are now closed, but you can speak to the scientists in person at the exhibition.