Efficient synthesis of nano high-entropy compounds for advanced oxygen evolution reaction

Developing efficient electrocatalysts for oxygen evolution reaction (OER) is imperative to enhance the overall efficiency of electrolysis systems and rechargeable metal-air batteries operating in aqueous solutions. High-entropy materials, featured with their distinctive multi-component properties, have found extensive application as catalysts in electrochemical energy storage and conversion devices. However, synthesizing nanostructured high-entropy compounds under mild conditions poses a significant challenge due to the difficulty in overcoming the immiscibility of multiple metallic constituents. In this context, the current study focuses on the synthesis of an array of nano-sized high entropy sulfides tailored for OER via a facile precursor pyrolysis method at low temperature. The representative compound, FeCoNiCuMnS_x, demonstrates remarkable OER performance, achieving a current density of 10 mA/cm² at an overpotential of merely 220 mV and excellent stability with constant electrolysis at 100 mA/cm² for over 400 h. The in-situ formed metal (oxy)hydroxide has been confirmed as the real active sites and its exceptional performance can be primarily attributed to the synergistic effects arising from its multiple components. Furthermore, the synthetic methodology presented here is versatile and can be extended to the preparation of high entropy phosphides, which also present favorable OER performance. This research not only introduces promising non-noble electrocatalysts for OER but also offers a facile approach to expand the family of nano high-entropy materials, contributing significantly to the field of electrochemical energy conversion.