Is nitrogen doping of diamond-like carbon films a viable strategy for bipolar plates in proton exchange membrane fuel cells?

In response to escalating climate change concerns, the transition to renewable energy systems, including hydrogen-based technologies, is imperative. Proton exchange membrane fuel cells (PEMFCs), which produce electricity through the electrochemical reaction of hydrogen and oxygen without greenhouse gas emissions, are at the forefront of this transition. However, the widespread commercialization of PEMFCs is hindered by the high cost and performance demands of bipolar plates (BPPs), which currently depend on noble metal coatings for corrosion resistance, thus compromising the popularization of this important technology for the upcoming energy transition. This study investigates hydrogenated diamond-like carbon (DLC) films, including nitrogen-doped variants, deposited onto aluminium alloy substrates as a potential low-cost alternative for BPP applications. Contrary to previous reports, we demonstrate that nitrogen doping significantly impairs the corrosion resistance and interfacial electrical conductivity of DLC coatings under simulated PEMFC conditions. These results highlight the complex interactions between doping elements and DLC film properties, emphasizing the need for further mechanistic studies. Despite the limitations of nitrogen doping, the use of non-nitrogenated DLC-coated aluminium remains as a promising approach to reduce material costs and enhance the sustainability of PEMFC technologies.