Bifunctional Platinum-Free Mixed Metal Oxygen Electrocatalysts Based on Naturally Abundant Peat

A functioning hydrogen economy requires efficient ways of producing and utilizing hydrogen via electrolyzers and fuel cells. The commercialization of these devices is well underway but their considerable capital costs still inhibit faster adoption by society1,2. One pathway towards more inexpensive devices is by tackling their respective bottlenecks, the oxygen evolution and reduction reactions, which currently require catalyst materials comprised of scarce precious metals. Intensive research is being conducted to introduce and develop suitable replacements for these catalysts. In this field, non-platinum group metal (NPGM) type catalysts have gained significant attention2,3. We present several NPGM-type oxygen electrocatalysts synthesized by modifying peat-derived carbon with nitrogen and different combinations of transition metals (Fe, Co, Ni). The obtained catalysts were characterized with various methods to elucidate their structure-reactivity relations. Namely, SEM-EDS was used to confirm that the modification of peat-derived carbon was successful. Additionally, the various metal alloy species found in the catalysts were identified via X-ray diffraction analysis. The excellent bifunctional electrocatalytic activity of the peat-based materials towards oxygen evolution and reduction was confirmed with rotating disc electrode measurements conducted in a 0.1 M KOH solution. Correlations between the physical and electrochemical properties of the catalysts were established and analyzed. Acknowledgments This work was supported by the EU through the European Regional Development Fund under projects TK141 “Advanced materials and high-technology devices for energy recuperation systems” (2014-2020.4.01.15-0011), NAMUR “Nanomaterials - research and applications” (3.2.0304.12-0397), PRG676 “Development of express analysis methods for micro-mesoporous materials for Estonian peat derived carbon supercapacitors” (01.01.2020–31.12.2024) and PUT1581 (1.01.2017–31.12.2020). References E4tech, 2021, The Fuel Cell Industry Review 2020. C. Lei, S. Lyu, J. Si, B. Yang, Z. Li, L. Lei, Z. Wen, G. Wu, Y. Hou, ChemCatChem 2019, 11, 5855. L. Osmieri, J. Park, D. Cullen, P. Zelenay, D. Myers, K. Neyerlin, Curr Opin Electrochem 2021, 25, 100627. Figure 1