High-Entropy Spinel Ferrite Nanoparticles Via Low-Temperature Synthesis for the Oxygen Evolution Reaction

High-entropy oxides are a material class that is currently receiving rapidly increasing attention due to the large variety in composition and adjustable properties. Cooperative effects between different metal cations in the crystal structure in addition to entropic phase stabilisation have proven beneficial for electrocatalytic applications. Most synthesis methods, however, require high synthesis temperatures and long synthesis times, and often only yield selected samples in good phase-purity.<br/>We herein present for the first time a microwave-assisted low temperature synthesis of earth-abundant high-entropy oxide nanoparticles. Phase-pure spinel ferrites (AFe₂O₄) of various compositions ranging from one to seven different A-cations were successfully obtained after only 30 min synthesis time at 225 °C. A detailed characterisation of their properties in relation to their composition was performed, and they were also employed for the alkaline oxygen evolution reaction (OER).<br/>A partial replacement of Fe by Co moreover shows the high versatility of the synthesis that also allows for the simultaneous variation of the B-ion.<br/>Moreover, we will present our latest results on preparing high-entropy thiospinel (M3S4) nanosheets with a similar low-temperature synthesis, incorporating up to 8 cations for entirely phase-pure electrocatalysts.<br/><br/>J. Zander, J. P. Wölfel, M. Weiss, Y. Jiang, N. Cheng, S. Zhang, <b>R. Marschall</b>, Adv. Funct. Mater. 34 (2024) 2310179.