In order for the reactions to occur in a fuel cell, battery and electrolyser, a catalyst must be used. Catalysts work by lowering the energy hump that the reacting species need to overcome and so increasing the chance of a successful reaction. Catalysts in fuel cells are mainly made from platinum metal, which is expensive and rare. For this reason, a number of techniques are used to reduce the amount of platinum in the fuel cell electrodes:
- Nanoparticles of Pt are used. As the reactions happen on the surface of the Pt, increasing the surface area to volume ratio reduces the amount of Pt you have to use to give the same reactivity.
- Pt nanoparticles are supported on carbon particles to help disperse them evenly throughout the electrode and make sure each catalyst particle is available for reaction.
- Pt is sometimes alloyed with other metals such as ruthenium or palladium.
Work at UCL
Using a UCL-patented method, Gyen produces platinum catalysts that take advantage of the unique properties of 2D materials, such as graphene’s high surface area and conductivity, to reduce the amount of platinum required and greatly enhance durability.
Zahra’s research involves synthesising novel non-PGM material to catalyse the ORR (oxygen reduction reaction) reaction at the cathode. This includes working with various transition metal alloys and carbon frameworks with the overarching aim to produce a low-cost and durable catalyst.
It is hoped that this will help reduce the price of fuel cells to a level where they are commercially viable for automobile applications. As well as cost, durability is important and the catalyst must last for many thousands of hours of operation. Though the catalyst does not get used up in the fuel cell reaction, it can corrode or detach from the carbon support over time which reduces the effectiveness of the fuel cell.
A cheap, durable and effective catalyst is vital for the future of fuel cells as a viable clean technology. The catalyst is at the heart of the chemistry of the fuel cell and so it is one of the most crucial areas of research and has a big influence on the performance of the cells.