Tailored Cation Distribution in High-Entropy Mn–Co–Ni–Cu–Zn Oxides: Toward Advanced OER Electrocatalysis

Abstract

Water splitting is a highly promising technology for renewable energy and energy storage. The primary challenge is to develop cost-effective, improved, long-lasting, and highly efficient electrocatalysts for the oxygen evolution reaction (OER). High-entropy oxides (HEOs) are the next generation of nanomaterials due to their complexity and significant role in modern scientific research. In this work, a layered structured (MnCoNiCuZn)O HEO is prepared using a simple metal–organic framework (MOF)-assisted strategy, and the effect of increasing cation concentration on the performance of the OER is evaluated. The chemical bonding interaction of this structure was revealed by XPS and EDS mapping techniques, demonstrating favorable electronic conductivity for optimizing the OER performance in the alkaline medium. Among the different cation variations, the HEO with an equal concentration of cations exhibits the lowest overpotential of 319 ± 5 mV @ 50 mA cm^–2, accompanied by a Tafel slope of 78 ± 7 mV dec^–1. Even at higher current densities, the HEO material exhibits the lowest overpotential, as evidenced by the Tafel values. This study suggested a design for HEO-based electrocatalysts, which achieves admirable water-splitting efficiency for sustainable hydrogen and oxygen production.