Factors Influencing Activity and Electrochemical Stability of Ru-Based Oxygen Evolution Electrocatalysts

A hydrogen-based energy economy is a viable candidate to provide clean power and alleviate carbon emissions produced by hydrocarbon-based fuels. Hydrogen produced by proton exchange membrane water electrolysis (PEMWE) provides a path to clean affordable energy; however, PEMWE costs are still too high for wide-scale market adoption. Electrochemical splitting of water is energetically hindered by the oxygen evolution reaction (OER) which has sluggish kinetics, and the benchmark OER catalyst iridium oxide (IrO 2 ) has high costs and very limited global supply. Ruthenium oxide (RuO 2 ) provides a higher activity and lower cost compared to IrO 2 ; however, under the high potential and highly acidic environment required for OER, RuO 2 shows lower stability compared to IrO 2 . Our prior study demonstrated that Ti-substitution within RuO 2 improved electrochemical stability, but also resulted in lower activity. 1 Here, we expand our study by exploring the effects of phase, composition, surface structure, electrolyte, and operating voltage on the activity and electrochemical stability of Ru-based OER catalysts to identify key contributing factors towards improving the electrochemical stability. Catalysts materials were synthesized using wet-chemistry or high energy ball milling, and commercial materials were used for comparison and baselining. Structure was determined using X-ray diffraction, scanning electron microscopy, porosimetry measurements, and x-ray photoelectron spectroscopy. We evaluate electrochemical OER activity and stability using rotating disk electrode electrochemistry, coupled with inductive coupled plasma mass spectrometry for analysis of dissolved metals within the electrolyte. We develop structure-activity-electrochemical stability correlations to determine driving factors influencing degradation and provide a pathway to the development of materials with improved catalyst performance and lower cost. References Godínez-Salomón, J. F.; Ospina-Acevedo, F.; Albiter, L.; Bailey, K.O.; Naymik, Z.G.; Mendoza-Cruz, R.; Balbuena, P.B.; Rhodes, C.P., ACS Appl. Nano Mater. 2022 , 5, 11752-11775.