Coating optimisation for fabrication of 3D printed electrodes used in hydrogen technologies

Abstract

The transition to climate-neutral energy systems creates the need for efficient and cost-effective hydrogen-based electricity generation. Proton Exchange Membrane Fuel Cells (PEMFCs) are central to this transition, offering clean and direct conversion of green hydrogen into electricity. However, their scalability is hindered by reliance on platinum (Pt), an expensive and scarce catalyst. To optimise the Pt usage, four methods were compared for applying Nafion and Pt/C (carbon supported Pt) in water/IPA (2-propanol): jetting, hand spray coating (HSC), air spray coating (ASC) and ultrasonic spray coating (USC). The Pt/C coatings were applied onto 3D printed meshes, which offer high surface area, high conductivity and chemical durability. The electrodes, coated with an optimal (medium) loading of 0.77 mgPt/cm² were assessed for their coating uniformity and performance using optical microscopy, SEM, EDS and electrochemical testing. A maximum power density of 4.67 mW/cm² was achieved with ASC but it used the most Pt during coating. The jetting coating resulted in the lowest performance (2.67 mW/cm²) but was the most Pt-efficient. USC provided a balance between a maximum power density of 4.07 mW/cm² and a medium Pt usage for the coating. These results can help guide the selection of the optimal method for scaling-up depending on CAPEX and OPEX, electrode performance and efficiency as well as sustainability concerns.