Hydrogen by Water Electrolysis

Hydrogen production by water electrolysis in water electrolyzers (WEs) has been developed as an alternative and sustainable technology for energy conversion and storage and is well integrated into the electric grid of the renewable energy system. However, hydrogen produced by electrolysis using current methods is more expensive than hydrogen produced by other technologies. Therefore, water electrolysis accounts for a mere 4% of global hydrogen production; all other production sources are linked to fossil fuels. Hydrogen produced by water electrolysis will only be competitive when the cost of the process is reduced and its stability is improved.

Proton exchange membrane (PEM) water electrolysis systems offer several advantages over traditional electrolysis technologies and have the potential to be cost effective at large scales. But, significant advances are needed in catalyst and membrane materials as well as in the labor-intensive manufacturing process. The state-of-the-art anode catalyst in conventional PEMWEs are iridium oxide or mixed oxide with ruthenium. Typical catalysts for commercial electrodes have iridium oxide loading from 1 to 3 mg cm^-2. This level of catalyst loading is too high to meet the long-term cost targets for energy markets. Furthermore, the translation of catalyst development from lab scale to the megawatt scale using current electrolysis technology is challenging in terms of catalyst cost and stability.

The enhancement of catalyst stability is as important as the reduction of catalyst loading. Long-term operation (up to thousands of hours) at high current density is particularly challenging with an Ir loading of less than 1 mg cm^-2.

Dr. Maric’s group is working to develop proton exchange fuel cells (PEMFC) that satisfy the Department of Energy’s 2020 electrocatalyst and membrane electrode assembly (MEA) performance and durability targets using a system of low-PGM-content electrocatalysts deposited on corrosion-resistant carbon supports, applied onto ultra-thin membranes, to ensure applicability in high-power-density, self-humidifying automotive fuel cell stacks.

We devote specific attention to achieving a high-performance low-Pt electrode structure, with a total loading of 0.15 mg/cm², by developing a gradient cathode structure, prepared using the reactive spray deposition technology (RSDT), which will be optimized for different carbon supports and ultra-thin membranes. The RSDT technique allows for independent, dynamic control of each element of the catalyst layer as it is directly deposited onto the electrolyte membrane. We mitigated the impact of low Pt loading on electrocatalyst durability in an electrode by studying and understanding ionomer-support-catalyst interactions and electrode microstructure evolution at the triple-phase boundary upon exposure to automotive drive cycles (or their AST equivalents).