Researchers at University College London, Queen Mary University of London and Humboldt Universität zu Berlin have suggested a design for a hydrogen fuel cell, with graphene as a key component. The new research promises to address some of the roadblocks that have thus far hindered the development of this clean, non-toxic, renewable technology, thus opening up hydrogen fuel cells as a potential clean-energy breakthrough.
At the moment the US Department of Energy estimates that the cost of energy generated by hydrogen fuel cells is around $61 per kilowatt. The ultimate aim is to get this down to $30 per kilowatt. The scaling up in the production of graphene-coated nanoparticles suggested in the paper could help significantly in this quest. The team’s findings could also extend beyond the field of fuel cells, lending itself to some exciting technological applications.
Hydrogen fuel cells are a method of converting chemical energy to electrical energy with only one by-product — water. As such they are not just clean and renewable, but also non-toxic. Such fuel cells rely on what is known as a polymer electrolyte membrane (PEM) to function — a barrier that can simultaneously allow the conduction of protons, separate gases, and electrically insulates the fuel cell’s electrodes.
Of the materials suggested for the construction of such a membrane, referred to as an electrode support material, graphene leads the way. It is resistant to corrosion, highly conductive and possesses a large surface area. Factor into this, a high-resistance to acidic conditions and its incredibly light-weight nature and the graphene/ fuel cell combination seems like a perfect match.
But there are still major problems that stand in the way of the widespread adoption of graphene-based hydrogen fuel cell technology. Graphene-based electrodes can suffer from high-defect concentrations arising from a non-uniform coverage of nanoparticles, both of which can negatively impact performance. This problem only gets worse during the cell’s lifecycle and nanoparticles get stripped from the graphene.
The solution the team suggested involves the creation of platinum nanoparticles coated with layers of graphene. Such particles, according to the team, are of the optimal dimensions to be uniformly dispersed across a surface. In this way, they can be used to coat an electrode in such a way that efficiency drops are all but eliminated.
This results in high catalytic activity, with the graphene’s durability providing remarkable stability over an operating lifetime of 30,000 charge/ recharge cycles.
The team’s research represents the first time that uniformly scaled platinum nanoparticles have been grown on graphene support with low defects. The team believes that the method they utilized, combined with the synthesis of charged graphene dispersion using what is known as the “metal-ammonia” method, makes their technology scalable.
Promisingly, in tests conducted thus far, their advancement seems to be matching both the performance and mechanism of a highly-optimized commercial platinum/carbon catalysts, whilst actually outperforming them in terms of stability.
What makes this synthesis method especially exciting is the fact that the team believes it can be turned to spreading different metals across a graphene structure. With these different metals comes the possibility of adapting to a variety of different applications. This could extend beyond just fuel cells and catalyst systems, to devices such as sensors and supercapacitors.