A research team at the University of California, Los Angeles led by materials science and engineering professor Yu Huang has developed a new design for a hydrogen fuel cell catalyst that can last more than 200,000 hours. This is almost seven times longer than the target figure for heavy-duty vehicles set by the U.S. Department of Energy.
For trucks that travel long distances, batteries can be inefficient: they take a long time to charge, which makes them difficult to operate. Hydrogen fuel cells offer an optimal alternative: they charge quickly, are environmentally-friendly and can achieve high power. Fuel cells generate electricity by converting hydrogen, emitting only water vapor as a byproduct. However, a catalyst is required to speed up chemical reactions in the system. Platinum-based alloys were previously used for that purpose, but they lost efficiency over time due to the leaching of other metals under high loads.
In order to solve this problem, the scientists embedded ultra-thin nanoparticles of pure platinum into protective pockets made of graphene, a strong and conductive material that consists of a single layer of carbon atoms. The particles were then nested inside the porous carbon structure of Ketjenblack, a material that made the catalyst both highly stable and efficient.
Tests showed that the new system provides an output power of 1.08 watts per square centimeter, which makes it comparable to conventional batteries, but eight times lighter. At the same time, it exhibits a power loss of less than 1.1% after 90,000 load cycles. Today, a power loss of 10% after 90,000 cycles is typically considered excellent, equating to more than ten years of operation. The new catalyst significantly exceeds the current target of 30,000-hour service life for proton-exchange membrane hydrogen fuel cells.
This means that the new technology effectively solves two key problems at once, providing a combination of high activity and durability. This makes hydrogen fuel cells a promising solution for long-haul trucking. Generally speaking, conversion of heavy trucks to hydrogen fuel could make a large impact on greenhouse gas emissions reduction, since these vehicles account for a quarter of emissions from transport despite making up just 5% of the world’s vehicle fleet.
