Graphene catalysts for longer-lasting fuel cells
A research team led by University College London (UCL) has produced graphene via a special, scalable technique and used it to develop hydrogen fuel cell catalysts. Writing in the journal Nanoscale, they revealed that this new type of graphene-based catalyst was more durable than commercially available catalysts and matched their performance.
Hydrogen fuel cells convert chemical energy into electrical power by combining hydrogen and oxygen with the aid of catalysts. As the only by-product of the reaction is water, they provide an efficient and environmentally friendly power source. Platinum is the most widely used catalyst for these fuel cells, but its high cost is a big problem for the commercialisation of hydrogen fuel cells.
To address this issue, commercial catalysts are typically made by decorating tiny nanoparticles of platinum onto a cheaper carbon support; however, the poor durability of the material greatly reduces the lifetime of current fuel cells. As noted by UCL Professor Dan Brett, a big barrier to the widespread commercialisation of hydrogen fuel cells is “the ability for catalysts to withstand extensive cycling required for their use in energy applications”.
Previous research has suggested that graphene — made from a single layer of carbon atoms arranged in a hexagonal lattice — could be an ideal support material for fuel cells due to its corrosion resistance, high surface area and high conductivity. However, the graphene used in the majority of experiments to date contains many defects, meaning that the predicted improved resistance has not yet been achieved.
The UCL team solved this problem by producing high-quality graphene decorated with platinum nanoparticles in a one-pot synthesis — a process that could be scaled up for mass production. The researchers confirmed the durability of their graphene-based catalyst using a type of test based on those recommended by the US Department of Energy (DoE), known as accelerated stress tests, and showed that loss in activity over the same testing period was around 30% lower in the newly developed graphene-based catalyst compared with commercial catalysts.
“The DoE sets tests and targets for fuel cell durability, with one accelerated stress test to simulate normal operating conditions and one to simulate the high voltages experienced when starting up and shutting down the fuel cell,” said UCL PhD student Gyen Ming Angel, first author of the study.
“Most research studies in the graphene space only evaluate using one of the recommended tests. However, since we have high-quality graphene in our material, we have managed to achieve high durability in both tests and under long testing periods, which is important for the future commercialisation of these materials. We look forward to incorporating our new catalyst into commercial technology and realising the advantages of longer-life fuel cells.”
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