Solar nanotech

Putting sunshine in the tank – using nanotechnology to make solar fuel.

Introduction

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?

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.

See all exhibits from 2011