EPSRC logo

Details of Grant 

EPSRC Reference: EP/Y013646/1
Title: Photocatalytic Heterojunction Z-schemes for Sustainable Hydrogen Production
Principal Investigator: Hyett, Dr G
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Department: Sch of Chemistry
Organisation: University of Southampton
Scheme: Standard Research
Starts: 01 May 2024 Ends: 30 April 2027 Value (£): 530,495
EPSRC Research Topic Classifications:
Materials Characterisation Reactor Engineering
Sustainable Energy Vectors
EPSRC Industrial Sector Classifications:
Related Grants:
Panel History:  
Summary on Grant Application Form
This project will pioneer a new and highly efficient approach to the generation of hydrogen by combining heterojunction photocatalysts into Z-scheme arrangements. This will allow for the splitting of water into hydrogen and oxygen, using sunlight as the energy source, with an order of magnitude improvement over current state of the art photosystems. This "solar" hydrogen can be stored and subsequently used as a fuel or in fertiliser production, and is a sustainable and decarbonised source of hydrogen - in contrast to current production which requires natural gas.

The impact of a source of sustainable hydrogen can be considered from several viewpoints. Energy storage is a key challenge as the UK switches to predominant use of renewable energy sources such as solar and wind, and away from natural gas and other fossil fuels. Conventional solar panels have a mismatch between winter electricity demand and generation biased towards the summer. In contrast, direct solar water splitting provides a complimentary class of solar energy, at lower cost, where the hydrogen can be stored during high production periods before conversion to electricity on demand when renewable energy supply is low. Hydrogen is also a valuable commodity chemical in its own right, for example in the production of ammonia for fertilisers. The ability to produce hydrogen using solar energy, and decrease dependence on natural gas, is a key component in tackling climate change while also enhancing energy security - which directly affects national security as recent events have shown.

Large scale pilot studies have confirmed that photocatalytic systems can achieve complete water splitting into hydrogen and oxygen, but have not yet breached the 0.5% solar to hydrogen (StH) efficiency needed for the energy breakeven point, and are far from the ultimate target of 10% StH necessary for commercially viable 'green hydrogen' production. Our project will take the next steps needed to achieve this target.

In photocatalysis, energy from sunlight is used to generate high energy electrons in the catalyst, leaving behind holes. These high energy electrons then drive the water splitting reactions at the surface of the catalyst. In order to achieve high efficiency, the photocatalyst must be able absorb a large fraction of the solar spectrum, prevent the electrons from recombining with their holes, and finally still maintain sufficient energy or overpotential to catalyse water splitting. We propose to combine two research strands to produce a new type of photosystem which can meet all three of these criteria. The first strand is the recent work on heterojunction photocatalysts. These are composed of particles of two different materials which allow for effective separation of the electron from the hole by trapping these in different parts of the catalyst, but which by themselves lack sufficient overpotential to carry out complete water splitting. The second strand is the work on 'Z-schemes' in which separate photocatalysts are used to maximise overpotential, by having an excited election transfer from one material to another to be 'boosted' by a second photon to a higher energy level to achieve water splitting. However, in Z-schemes the transfer process is slow, allowing time for recombination of the electrons and holes, reducing efficiency.

We propose that by combining the heterojunction photocatalysts in a Z-scheme arrangement, it will be possible to create a photosystem that finally meet all three challenges. The heterojunctions will supress recombination, the Z-scheme will allow for large overpotential, and the system can make use of visible light absorbers to maximise solar energy uptake. We believe that because of the recent developments in visible light active heterojunctions, Z-scheme photosystems and demonstration of scale up, the time is now ripe to combine these research threads into a single photocatalytic system to achieve high efficiency water splitting.

Key Findings
This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
Potential use in non-academic contexts
This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
Description This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
Date Materialised
Sectors submitted by the Researcher
This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
Project URL:  
Further Information:  
Organisation Website: http://www.soton.ac.uk