Understanding the Self‐Reconfiguration Properties of a Novel Spinel‐Type High‐Entropy Catalyst

Abstract High‐entropy oxides (HEOs), known for their excellent thermodynamic stability due to their high‐entropy effect. In this study, high‐entropy (Ni x AlCoCrMn) 3 O 4 oxides of spinel structure were synthesized by sol‐gel method. This HEO has a self‐reconfiguration properties in the reaction, and its internal Ni and Co ions exsolve to form a uniformly dispersed NiCo alloy on the surface. The increase of Ni content promotes the exsolution of Ni and Co ions from the interior of the spinel. The high‐entropy with a large number of oxygen vacancies not only possesses a stable structure to limit the migration of NiCo alloys, but also enhances the hydrogen overflow. In the CO methanation reaction, it has 99 % CO conversion with 87 % methane selectivity within 400 °C, and it is stable in the long‐term test. This work provides a new idea for exploring the use of high‐entropy materials to improve thermal catalytic activity and stability.