Nitrogen-Containing Perovskite Nanoparticles for Photocatalytic Water Splitting

Hydrogen (H2) is a widely used industrially important chemical, for example in the production of ammonia to make fertilisers. However, the vast majority of hydrogen is currently produced from fossils fuels in a process which releases carbon dioxide (CO2). Hydrogen also has potential as a way of storing renewable energy in the form of a carbon-neutral fuel. This fuel may then be transported elsewhere, to be burnt wherever, and whenever, the energy is needed. Therefore, new and improved methods of generating hydrogen with renewable energy will be critical for meeting climate change targets for net-zero emissions, and for developing a secure energy system for the future.
Photocatalytic water splitting is a promising method for producing hydrogen using renewable solar energy. Energy from sunlight is used to generate hydrogen and oxygen gases directly from water, with the help of a photocatalyst. No electricity is needed, and the process doesn't release carbon dioxide. The role of the photocatalyst is to absorb the incoming light and excite electrons to a higher energy state where they can use that extra energy to split a water molecule into H2 and O2.
Producing hydrogen from fossil fuels is currently significantly cheaper than producing it with either renewable electricity or sunlight, so significant improvements to photocatalysts are needed to ensure they have very high efficiencies and minimal cost. This will require the design and optimisation of photocatalyst materials to ensure they meet these goals. This involves absorbing as much of the incoming sunlight as possible, from high energy UV light through to the lower energy visible light. It also means ensuring that as much of the energy absorbed by the photocatalyst goes into producing hydrogen as possible, and little is wasted in other processes such as recombination.
The focus of this project is on a perovskite oxynitrides, a class of materials that show promising potential as photocatalysts. These materials have low bandgaps, allowing absorption of a large section of the solar spectrum, and can be easily modified through substitution of different elements. This allows tuning of their electronic, magnetic and structural properties to improve their photocatalytic ability. These properties will be determined with a variety of different experimental techniques to assess which photocatalysts work the best and understand the mechanisms underpinning their performance. This knowledge will then be fed back into future photocatalyst design.
Through the development and optimisation of these novel photocatalytic materials, the boundaries of photocatalytic water splitting will be pushed to achieve higher efficiencies, and lower hydrogen costs, to enable industrial viability and the step-change in green hydrogen production the world needs.
This project falls within the EPSRC Energy and Decarbonisation theme and the EPSRC Materials for Energy Applications area.