Epitaxial growth of metal-organic framework nanosheets into single-crystalline orthogonal arrays

Construction of two-dimensional nanosheets into three-dimensional regular structures facilitates the mass transfer and exploits the maximum potential of two-dimensional building blocks in applications such as catalysis. Here, we report the synthesis of metal-organic frameworks with an orthogonal nanosheet array. The assembly involves the epitaxial growth of single crystalline metal-organic framework nanosheets with a naturally non-preferred facet exposure as the shell on a cubic metal-organic framework as the core. The nanosheets, despite of two typical shapes and crystallographic orientations, also form a single crystalline orthogonally arrayed framework. The density and size of nanosheets in the core-shell-structured composite metal-organic frameworks can be well adjusted. Moreover, metal-organic frameworks with a single composition and hollow orthogonal nanosheet array morphology can be obtained. Benefiting from the unusual facet exposure and macroporous structure, the designed structure exhibits improved electrocatalytic oxygen evolution activity compared to conventional nanosheets. Constructing regular 3D superstructures from 2D nanosheets is a challenge. Here, the authors report the epitaxial growth of MOF nanosheets into single-crystalline orthogonal arrays with enhanced functional properties.

Automated summary

Constructing regular three-dimensional structures from two-dimensional nanosheets is challenging but holds great potential for enhancing their functional properties. In this study, the authors synthesized metal-organic frameworks with an orthogonal nanosheet array by epitaxially growing single crystalline nanosheets as shells on a cubic metal-organic framework core. The resulting structure exhibited improved electrocatalytic activity for oxygen evolution compared to conventional nanosheets. The density and size of the nanosheets in the core-shell structure could be adjusted, and metal-organic frameworks with a single composition and hollow orthogonal nanosheet array morphology were also obtained.