Screening of Perovskites as Oxygen Evolution Reaction Catalysts in Alkaline Environment Tested Under Industrially Relevant Conditions

In recent years the research in catalyst development for the Oxygen Evolution Reaction (OER) in alkaline media has focused on finding the catalytically most active materials. Furthermore, catalysts are usually tested in an RDE setup at room temperature in 0.1 or 1 M concentrated KOH solution, which is far from industrial application conditions, where commonly temperatures between 70-100 ⁰C and highly concentrated electrolyte (6-10 M KOH) are used [1]. This is problematic as the material response is very different at higher temperatures and concentration of electrolyte. The expected thermally activated OER performance is often accompanied by severe degradation, observed already after short-term operation at industrially relevant conditions [2]. Eventually this results in severe loss in performance. For example, Pascuzzi et al. reported fast electrode degradation at industrial operating conditions (75 ⁰C; 10 M KOH and 100 mA/cm2) due to the breakdown of the platelet-like morphology of NiFeOxHy layered double hydroxide (LDH) [3]. While the long-term durability of NiFeOxHy LDH remains questionable, with conflicting findings suggesting a rather complex interplay between structure-composition-operating conditions and activity-stability, perovskites offer an interesting alternative as they can accommodate a broad range of elements on both the A- and B-site, allowing for tuning the material properties. Perovskite catalysts have in some cases shown good activity and stability, one good example is PrBa0.5Sr0.5FexCo2-xO5+ 𝛿, which showed an overpotential of 290 mV at 10 mA/cm2 and stable operation for 2000 h in 1 M KOH [4]. However, in most cases critical raw materials (CRM) are involved in high performance perovskite catalysts. Furthermore, the stability of the host perovskite remains a challenge under industrial OER conditions even for rather stable perovskite compositions. For instance, Adolphsen et al. observed the formation of secondary phases in La, Ni and Fe based perovskites at 100 ⁰C when immersed in 31 wt.% KOH electrolyte [5]. In this study the performance and stability of different perovskite materials, including some of the most prominent OER perovskite catalyst materials from the literature, are explored at room temperature and at industrial operating conditions. Our tests of the most prominent catalyst materials show low stability and strong signs of decomposition at industrial operating conditions. [1] Zeng, K., & Zhang, D. (2010). Recent progress in alkaline water electrolysis for hydrogen production and applications. Progress in Energy and Combustion Science, 36(3), 307–326. https://doi.org/10.1016/j.pecs.2009.11.002 [2] Lohmann-Richters, F. P., Renz, S., Lehnert, W., Müller, M., & Carmo, M. (2021). Review—Challenges and Opportunities for Increased Current Density in Alkaline Electrolysis by Increasing the Operating Temperature. Journal of The Electrochemical Society, 168(11), 114501. https://doi.org/10.1149/1945-7111/ac34cc [3] Etzi Coller Pascuzzi, M., Man, A. J. W., Goryachev, A., Hofmann, J. P., & Hensen, E. J. M. (2020). Investigation of the stability of NiFe-(oxy)hydroxide anodes in alkaline water electrolysis under industrially relevant conditions. Catalysis Science and Technology, 10(16), 5593–5601. https://doi.org/10.1039/d0cy01179g [4] Jo, H., Yang, Y., Seong, A., Jeong, D., Kim, J., Joo, S. H., Kim, Y. J., Zhang, L., Liu, Z., Wang, J. Q., Kwak, S. K., & Kim, G. (2022). Promotion of the oxygen evolution reaction: Via the reconstructed active phase of perovskite oxide. Journal of Materials Chemistry A, 10(5), 2271–2279. https://doi.org/10.1039/d1ta08445c [5] Adolphsen, J. Q., Sudireddy, B. R., Gil, V., & Chatzichristodoulou, C. (2018). Oxygen Evolution Activity and Chemical Stability of Ni and Fe Based Perovskites in Alkaline Media. Journal of The Electrochemical Society, 165(10), F827–F835. https://doi.org/10.1149/2.0911810jes