Natalie Page¹, Naohiro Fujinuma^1,2, Jeffrey Hettinger¹, Samuel E. Lofland^1
1Rowan University, Glassboro, NJ
²Sekisui Chemical Co., Ltd, Tokyo, Japan
Electrocatalysts demonstrate significant promise for sustainable processes like carbon capture and generating recycled carbon fuels which are needed to achieve net zero carbon emissions. However, the commercialization of these processes is limited by several factors, one of which is the high cost of catalysts. Oxygen evolution reaction (OER) is necessary for many sustainable electrocatalytic processes and among the highest performing industrial catalysts are iridium and iridium oxide which are extremely high cost and are limited in supply. The discovery and development of cheaper alternatives has been difficult due to constraints in experimental methodologies, scalability limitations, and a lack of understanding of reaction mechanisms. To accelerate OER electrocatalyst discovery, we investigated combinatorial Pt-Pd-Au-Ir thin film alloys using a novel scanning electrochemical device to efficiently screen the phase space for high-performing catalyst candidates. Combinatorial libraries of Pt-Pd-Au-Ir were sputter deposited on Si wafers. The wafers were mapped with electron dispersive spectroscopy and x-ray diffraction to identify chemical composition and crystal structure. Electrochemical measurements, including electrochemical impedance spectroscopy, cyclic voltammetry, and chronoamperometry, were done with 0.1 M H₂SO₄. From the differential Tafel plots, relationships between chemical composition and catalyst oxidation mechanisms were identified from machine learning analysis. We discovered stable and high performing Pt-Pd-Au-Ir catalysts with Ir content below 0.2 mgIrcm^-2 and currents above 42 A gIr^-1 at 1.6 V, the current benchmarks for OER. Due to their inherit resistance to corrosion and reduced cost associated with lower Ir content, these alloys are candidates for industrial implementation.