 Reduced the size of metal organic frameworks, MOFs, derivatives is an effective strategy to manipulate their phase engineering owing to size dependent oxidation. Herein, a spatial confined growth strategy is proposed to encapsulate small-size MOFs derivatives into hollow carbon nanocages. It realizes that the hollow cavity shows a significant spatial confinement effect on the size of confined MOF crystals and subsequently affects the dielectric polarization. This article was authored by Han Xiaosu, Guo Zhengjiang, Yi Wang, and others.