Background
Martyn-Pemble

Researchers at Tyndall National Institute, Cork, are partnering with scientists from the United States and Northern Ireland to unlock the energy potential in water. The project aims to use semiconductor materials and sunlight to isolate energy-laden hydrogen in water by replicating processes found in nature.

The €1million initiative, entitled ‘Research into Emerging Nanostructured Electrodes for the Splitting of Water’ (RENEW), is led by Professor Martyn Pemble and Dr Paul Hurley at Tyndall, Professor Paul McIntyre at Stanford University and Professor Andrew Mills at Queen’s University Belfast.

Borrowing from electronics, the researchers will first seek to create the optimum ‘artificial leaf’ using layers of semiconducting materials such as silicon. These would be water-resistant and used to ultimately create clean fuel by splitting the molecules of water into hydrogen and oxygen under natural conditions without any additional energy.

Stokes Professor of Materials Chemistry at Tyndall, Prof Pemble – one of four principal investigators for the project – explained: “The main focus for the project is a tiny, stacked arrangement of materials that is used for some transistors in the electronic industry. Previous work has shown that these structures can act as basic ‘artificial leaves’ for splitting water and the aim now is to make them more efficient.”

Professor Pemble added: “Professor McIntyre has shown that if you put the right metal on the surface of a silicon stack and provide light, then you can get it to oxidise water to give oxygen. Then, on another electrode connected to it – perhaps a platinum wire – the electrons that we have gained can be used to reduce water, and this produces hydrogen. So it only requires the sunlight to fall on this attack of layers where the water oxidation takes place. Then, according to Prof Andrew Mills, who is an acknowledged expert on photocatalysis, ‘the rest of the process is driven by the electrochemistry’.”

While previous similar processes for harvesting hydrogen for fuel have required the use of additional energy, or have been heavily reliant on the presence of ultra-violet light, RENEW will focus on using natural light and will experiment with a range of semi-conducting materials. Key to the process will be creating an impenetrable top layer that can withstand water’s corrosive effects, by a process known as atomic layer deposition.

Reflecting on the RENEW partnership, Professor Pemble noted, “We have been thinking about doing this for a long time – it is quite obvious that these layered structures can have other applications outside of electronics – and now we have got the opportunity to bring it forward. The ultimate goal is to combine our expertise to get to a point where you just drop the electrodes into water and when the sun comes out they would start to bubble away generating an unlimited, free and completely clean source of hydrogen, as well as oxygen.”

The RENEW project is expected to run for the next three years and is jointly funded by the National Science Foundation in the US, Science Foundation Ireland and the Department for Employment and Learning for Northern Ireland under the US-Ireland Research and Development Partnership Program.