Enhancing Proton Exchange Membrane Water Electrolysis Performance through Electrospray Catalyst Deposition.

Catalysts are among the key components limiting the large-scale development of hydrogen technologies. Despite intensive research into more affordable alternatives, most catalysts used in proton exchange membrane fuel cells (PEMFCs) and proton exchange membrane water electrolyzers (PEMWEs) still rely on expensive noble metals such as platinum, iridium, and ruthenium. To reduce costs without compromising performance, new strategies must focus on optimizing catalyst utilization. Electrospray deposition is emerging as a promising technique that enhances catalyst layer morphology, thereby increasing electrochemically active surface area while reducing the amount of catalyst required. Electrospray works by applying a high voltage (in the kilovolt range) between the tip and the substrate, leading to the atomization of the catalyst ink into nanodroplets. This process enables homogeneous deposition and improved layer structure compared to conventional methods. In this work, we present the development of an electrospray system specifically designed in our laboratory for use with catalyst inks in PEMWE electrodes. Both anode and cathode catalyst layers were fabricated by electrospray deposition and compared with conventional spray-deposited electrodes. Morphological analyses confirmed that electrospray produced smoother and more uniform catalyst films, resulting in larger electrochemically active areas. Polarization curve measurements demonstrated that the improved morphology directly enhanced electrolyzer performance, particularly by reducing mass transport losses. These results show that electrospray is a valuable technique for advancing catalyst layer engineering in PEMWEs, contributing in a close future to lower noble-metal loading and reduced system costs, while maintaining high performance.