Research carried out at the University of Birmingham, in collaboration with Royal Military College, Canada, explores new and cheaper ways of increasing the carbon monoxide (CO) tolerance, which will play a significant role in improving the durability of fuel cells and making them more cost effective.
Fuel cells are green electrochemical sources for energy generation that use hydrogen (or hydrogen based chemicals), as fuel, which combines with oxygen in the presence of platinum (Pt) based catalysts to produce electricity, water and heat.
Research has revealed important insights into the role of oxygen groups in graphene oxide in enhancing the tolerance of Pt nanoparticles toward CO poisoning. The current systems need ultrapure hydrogen, and CO poisoning is one of the key barriers to be overcome for enhancing the lifetime and usability of these systems.
Currently, the most effective way of increasing CO tolerance is the use of platinum alloys using oxophillic elements such as ruthenium, palladium and gold; an extremely costly solution. An enhancement in the CO tolerance of the platinum electrocatalysts systems for the aforementioned applications means: (a) the low temperature fuel cell systems would not require ultrapure hydrogen, and the process of hydrogen purification will become more efficient thereby reducing the existing costs significantly; (b) higher current and output power along with enhanced durability; (c) other processes such as hydrogenation of hydrocarbon which also face similar CO poisoning issues would become more effective and economical; and most importantly, (d) increased efficiency of platinum catalyse would mean reduced dependence on this rare, expensive and limited resource.
Researchers discovered when graphene oxide, made of sheets of nanostructured graphene with a variety of oxygen functional groups decorating the surface, are synthesized with Pt nanoparticles, the carboxyl group interacts with Pt in such a manner that any approaching CO molecule faces stronger spatial and electronic resistance, if it tries to bind to Pt atom.
Dr Surbhi Sharma, from the Centre for Hydrogen and Fuel at the School of Chemical Engineering at the University of Birmingham said:
“This research highlights the significance of tailoring the graphene oxide surface to have more of the required oxygen groups which can significantly enhance CO tolerance and eliminate the need for other expensive oxophillic materials, which is one step forward towards making fuel cells cheaper and more affordable.”