Coen de Graaf is doctor in Theoretical Chemistry and member of the research group in Quantum Chemistry of the URV. He is researching how to split water with sunlight so we can use the hydrogen as a source of energy

Fossil fuels make the world go round and one of the great challenges facing science is to find cheaper and more efficient energy sources

What are you currently researching?

I am researching how to split water with sunlight so we can use the hydrogen as a source of energy. Instead of splitting water using electricity, our research group is studying ways of doing so with sunlight, which is an inexhaustible, abundant and easy-to-access source of energy.

What is the current method used to split water?

Electrolysis. It’s been used since the 19th century for the decomposition of water, but it is not efficient because it requires a lot of electricity. Now, using computer simulations, we are researching the reactions caused by sunlight in certain transition molecules such as iron or ruthenium.

What do you need to decompose water?

We need free electrons. Electricity has them but sunlight does not. We have found that irradiating certain molecules in transition metals with sunlight generates free electrons that for a while can be used to attack the water. This works with ruthenium complexes but not with iron complexes because the reaction is too quick, the electron returns to metal very quickly and there is no time to do anything. The aim of our research is to make tests and changes to increase the time that these electrons are available so that they can split water when they come into contact with it.

So the challenge is to get iron to behave in the same way as ruthenium?

That is what we want to achieve, because iron is very cheap. We have a long way to go but many people are working on it and if we manage to decompose water to generate hydrogen, we will take a big step towards a more sustainable future in which we can generate energy ourselves.

Water, inexhaustible energy

How can energy be obtained from hydrogen?