Georgia Tech scientists have made use of selenium anchors to improve the durability and cost of platinum fuel cell catalysts.
Platinum catalysts, though renowned for enabling the oxidation reduction reaction in fuel cell technology, haven’t been able to win their way through the fuel cell market due to their prohibitive pricing.
This could all change thanks to Georgia Tech’s new platinum-based catalytic system that is far more durable and cost-effective than traditional commercial systems.
Sintering – a process in which particles of platinum migrate and clump together – is one of the key causes of degradation in platinum catalysts.
It reduces the specific surface area of the platinum thereby causing the catalytic activity to drop.
To reduce such sintering, the institute has developed a new technique that anchors the platinum particles to their carbon support material using bits of the element selenium.
Georgia Tech’s process starts by loading nanoscale spheres of selenium onto the surface of a commercial carbon support.
The selenium is then melted under high temperatures so that it spreads and uniformly covers the surface of the carbon.
Once this is done, the selenium is reacted with a salt precursor to platinum to generate particles of platinum smaller than two nanometers in diameter and evenly distributed across the carbon surface.
The covalent interaction between the selenium and platinum is what provides a strong link to stably anchor the platinum particles to the carbon.
Because of the increased specific surface area of the nanoscale platinum, the new catalytic system initially showed catalytic activity three and a half times higher than the pristine value of a commercial platinum-carbon catalyst.
The scientists then tested the catalytic system using an accelerated durability test.
Even after 20,000 cycles of electropotential sweeping, the new system still provided a catalytic activity more than three times that of the commercial system.
According to the scientists, this was on account of the selenium anchors that proved effective in keeping most of the platinum particles in place.
Image and content: Christopher Moore/Georgia Tech