Rare earth-incorporated high entropy oxides for energy and environmental catalysis

High entropy oxides have been regarded as one of the most promising catalysts. Their unique and diverse elemental compositions bring stable structures and abundant metal active sites to the catalysts. Notably, rare earth ions have similar radii, unique electron orbitals, and variable valence states. As a result, incorporating rare earth elements into high entropy oxides can effectively adjust the surface state of the catalyst, ultimately improving the structure and properties of the high entropy oxides. However, there is no systematic review on the development of rare earth-incorporated high entropy oxides. In this review, we target the structure, synthesis, and application of rare earth-incorporated high entropy oxides to summarize their research progress in catalysis in recent years. First, we provide an overview of three types of rare earth-incorporated high entropy oxides: fluorite-type, perovskite-type, and pyrochlore-type. Then, the main synthesis methods are discussed in detail, including solid-state reaction, nebulized spray pyrolysis, chemical co-precipitation, and solution combustion. Finally, we analyze the applications of this material in catalytic reactions and suggest possible challenges and solution strategies. It is concluded that this unique material has good prospects for development.