James Walker, PhD student at the University of Birmingham, explores the impacts that platinum market trends are having upon fuel cell commercialisation, and highlights some Birmingham research which aims to mitigate these impacts.
Platinum. Whether in a ring on your finger, in a filling in one of your teeth or in the catalytic converter in your car, you are likely more familiar with this versatile transition metal than you realise. Being a ductile, yet stable and corrosion-tolerant material, with established catalytic activity, platinum is a material in high demand. According to Johnson Matthey’s May 2015 Platinum Group Metal Market Report1, demand for platinum outstrips supply each year and this keeps prices high. So high, for example, that the average price of platinum between April 2015 and April 2016 was $982/oz2 (£25/g), which compares to just $43/oz2 (£1/g) for ruthenium, another transition metal.
In terms of energy generation, high platinum prices are bad news for fuel cells and the growth of the wider hydrogen economy, as platinum is widely used in Polymer Electrolyte Fuel Cells (PEFCs) to catalyse the oxygen reduction reaction essential to their operation. PEFCs have a range of possible low-carbon energy applications including in transport and portable power generation. In transport, fuel cell buses are on the roads in London and Aberdeen and passenger vehicles including the Toyota Mirai and Hyundai ix35 are entering fleets around the world (including that of the University of Birmingham!). In portable power, these fuel cells have been employed by Loughborough University spin-out Intelligent Energy in their Upp mobile phone charger. In both cases, these technologies have the advantage that the only emission produced during their operation is water and thus they can be used in the low-to-zero emission zones of the future, including city centres and national parks.
However, these vehicles and products occupy niche segments of their respective markets and in the transport case are currently usually only seen on the roads as part of feasibility studies. The high cost of the platinum catalysts required for these fuel cells (where up to 30% of the cost of a fuel cell can be attributed to the catalyst!3) is hampering mass market commercialisation efforts and limiting the opportunities for fuel cell technologies to compete with incumbents. As a result, much of the research underway within the PEFC community is focussed on reducing the loading of platinum, while retaining catalyst activity and durability. Although applied to a very specific problem, lessons learned in this research have implications for wider materials science, and in particular efforts to improve resource efficiency in other applications.
Within the Birmingham Centre for Hydrogen and Fuel Cell Research at the University of Birmingham, researchers are working on a number of different platinum-reduction (or indeed replacement) and optimisation projects. Many of these projects focus on the preparation of nano-scale alloys of platinum with other, cheaper elements. A number of our researchers are aiming to prepare core-shell nanoparticles and nanowires, with inexpensive cores composed of another metal covered in thin, high surface area shells of platinum. Others are aiming to swap platinum out altogether, replacing it with another catalytically active metal. Another stream of our research revolves around preparing optimised support materials upon which to deposit our catalysts, to enhance their durability and surface coverage.
Each of these projects involve electrochemical testing both in the lab and in fuel cell test stations, to assess how our novel preparations compare with commercially available platinum catalysts and support materials. More information about these research projects is available at www.fuelcells.bham.ac.uk and from the group’s Twitter page, @FuelCellsCDT.
- Johnson Matthey Precious Metals Management, Platinum Group Metal Market Report, May 2015.
- Johnson Matthey Precious Metals Management, Platinum Group Metal Monthly Price Reports, May 2015.
- Steinberger-Wilckens, Fuel Cells and Hydrogen Technology, lecture, unpublished.