The high cost of platinum, a valuable metal that is the main catalyst for the chemical reactions in next-generation hydrogen fuel cells, has been a barrier to the widespread adoption of this technology. However, scientists have engineered a platinum-cobalt alloy to act as a catalyst, greatly reducing the amount of platinum needed to achieve the same or even better performance. The novel platinum-cobalt electrocatalyst and the method used to produce it were reported in the Particuology journal on 15 December 2022.
In an effort to reduce the amount of platinum needed, researchers at the Beijing University of Chemical Technology have focused on diluting it with cobalt to form alloys that exhibit a greater “active surface area”, where the necessary chemical reactions can occur. However, finding the optimal balance of alloying to achieve the best ORR (oxygen reduction reaction) performance has been a challenge. Professor Zhonghua Xiang of the Beijing University of Chemical Technology synthesized a platinum-cobalt-carbon precursor using dimethylamine borane as a reducing agent and heated it to high temperatures in hydrogen and argon gas to produce a platinum-cobalt alloy with a 3:1 ratio of platinum to cobalt in the form of nanoscale particles.
Why it matters
Hydrogen fuel cells will be crucial in the transition to clean energy, particularly in sectors such as heavy transport that are difficult to electrify with batteries. However, the most commonly used fuel cell – the alkaline fuel cell – is fairly heavy and thus limited in its application in sectors such as shipping and aviation where space is at a premium. The next generation of fuel cells, proton-exchange membrane fuel cells (PEMFCs), are much more compact but require the use of expensive platinum as the catalyst for the ORR, which is a key reaction in PEMFCs.
The structure of the electrons in the platinum-cobalt alloy allows for a high level of activity on the surface of the electrolyte membrane, resulting in excellent ORR performance. In addition, the alloy’s stability in acidic conditions is significantly higher than that of pure platinum, making it a promising candidate for use as a catalyst in PEMFCs. While more research is needed to fully understand the potential of this platinum-cobalt alloy as a catalyst, it represents a significant step towards reducing the cost of fuel cell technology and promoting its wider adoption.