With the growing urgency to decarbonize energy systems, proton exchange membrane fuel cells (PEMFCs) have gained prominence as a clean power source. A critical barrier to their widespread adoption, however, lies in the cost and durability of bipolar plates (BPPs), essential components often reliant on expensive noble metals. In a recent study, we explored the use of hydrogenated diamond-like carbon (DLC) coatings, including nitrogen-doped variants, applied to aluminium alloy (AA6061-T6) substrates as a cost-effective alternative. Surprisingly, the findings challenge previous assumptions by showing that nitrogen doping degrades rather than improves key properties — namely corrosion resistance and interfacial contact resistance (ICR) — under PEMFC-relevant conditions. Our results question the idea of metal-carbon interfaces to achieve higher corrosion resistance in aluminium.
These results underline the complex behaviour of DLC coatings when modified with doping elements such as nitrogen. While nitrogen doping has previously been associated with enhanced performance in thin film applications, this study reveals that its effects in the harsh chemical and electrochemical environment of PEMFCs can be detrimental. Therefore, the authors call for more detailed investigations into the mechanisms by which doping influences DLC properties, particularly with respect to deposition conditions and operational stability. Despite the setbacks associated with nitrogen, undoped DLC-coated aluminium remains a promising and sustainable path forward in the development of next-generation PEMFC bipolar plates.
This article is part of our saga on proposing aluminium alloys as the next generation materials for bipolar plates. I am very happy we are getting very advanced in this topic!
Access the article in press here:
F.C. Silva, et al. Is nitrogen doping of diamond-like carbon films a viable strategy for bipolar plates in proton exchange membrane fuel cells? Vacuum, 2025, 114574, https://doi.org/10.1016/j.vacuum.2025.114574.
(https://www.sciencedirect.com/science/article/pii/S0042207X25005640)
Our past works on metal-metalloid interfaces to functionalise aluminium alloys as BPPs in hydrogen-based fuel cells can be found here:
ACS Materials Letters. 6(1), 2024, 4564–4570: https://pubs.acs.org/doi/abs/10.1021/acsmaterialslett.4c01303
International Journal of Hydrogen Energy 45(58), 2020, 33993-34010: https://doi.org/10.1016/j.ijhydene.2020.09.037
Thin Solid Films 710, 2020, 138268: https://doi.org/10.1016/j.tsf.2020.138268
SN Applied Sciences 2, 2020, 865: https://doi.org/10.1007/s42452-020-2617-3
Procedia Structural Integrity 13, 2018, 658-663: https://doi.org/10.1016/j.prostr.2018.12.109
Materials at Extremes 