Using ultrasonics as a non-invasive technique to evaluate coatings on substrates for electrochemical systems

Substrate deposition is crucial for various applications such as semiconductor manufacturing, photovoltaic cell production, and catalyst-coated electrodes for electrochemical systems, as it directly influences the quantity, cost, performance, and durability. Our study involves using a spray coating system to apply a platinum-based catalyst onto a gas diffusion layer (GDL) in tandem with a non-invasive technique to quantify the amount of platinum deposited on the surface. Currently, catalyst deposition is characterized by using lab-type evaluation methods, like scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray fluorescence (XRF), among others. While these ex-situ techniques can quantify catalyst amounts, they cannot measure the catalyst loadings during the deposition. They often require the substrate to be removed for analysis which can slow down the manufacturing process and inherently increase costs. Here, we introduce a non-destructive evaluation method that uses acoustic resonance spectroscopy (ARS) to characterize substrate depositions during the manufacturing process without compromising the manufacturing speed. And, because ARS is a highly sensitive technique, we’ve implemented a custom-made setup to maximize acoustic energy transfer between transducers while exciting the substrate. Results show shifts in the resonance spectrum directly proportional to amount of catalyst on the GDL.