Spinel/Rock Salt Core/Shell High-Entropy Oxides for Selective CO<sub>2</sub> Hydrogenation
Ke Wang, Wooseok Lee, Rui Zhang, Zijian Wang, Yu Zhang, Junseok Moon, Dongho Shin, Megalamane S. Bootharaju, Juan Du, Aibing Chen, Seoin Back, Taeghwan Hyeon, Shuyan Song, Hongjie Zhang, Xiao Wang
Abstract
High-entropy oxides (HEOs) exhibit exceptional structural stability through configurational entropy maximization, yet their catalytic activity can be inadvertently constrained by the inherent activity–stability trade-off arising from dynamic site regeneration limitations. Here, we present an entropy recombination strategy that designs a spinel/rock salt core/shell mixed-phase HEO catalyst. This catalyst, featuring a spinel-core entropy modulator, achieves thermodynamic equilibrium via compositional entropy exchange, resulting in an ultra-active thin rock salt shell HEO. The catalyst demonstrates superior mass activity (318 μmol CO g cat –1 s –1 at 380 °C) and stability in the reverse water gas shift reaction, surpassing Cu-based and even noble metal-based catalysts. The core/shell architecture facilitates a multicomponent surface, oxygen vacancy generation, and Cu exsolution, accelerating the redox pathway’s rate-determining step via enhanced hydrogen transport. This work represents a breakthrough in HEO structural engineering, with promising advancements in diverse catalytic applications.