Lattice Strain in High Entropy Oxides Promote CO2 Photomethanation

Abstract Lattice strain is widely investigated to improve the performance of heterogeneous catalysts, however, the effect of lattice strain is under‐explored in high‐entropy oxide based photocatalyst. In this study, noble‐metal‐free (CoCrMnFeNi)Ox with lattice strain is synthesized using a temperature‐controlled, template‐free and salt‐assisted strategy. In the presence of lattice strain, an intensive internal electric field is formed in (CoCrMnFeNi)Ox, promoting the separation of photoinduced charge carriers. The size of the (CoCrMnFeNi)Ox can be tuned by varying the calcination temperature. Specifically, (CoCrMnFeNi)Ox prepared at a higher temperature possesses a smaller grain size exposing more active sites, resulting in an enhanced CO 2 photomethanation performance. This work provides valuable insights for the rational design of the photocatalysts and highlights the promising role of high‐entropy oxides in heterogeneous photocatalysis.