Reversible Single-Crystal-to-Single-Crystal Transformations between Nanoscale 2D Nanosheets and 3D Metal-Organic Frameworks

Reversiblesingle-crystal-to-single-crystal (SCSC) transformationsbetween nanoscale three-dimensional ZIF-67 and two-dimensional Co-LDH(LDH = layered double hydroxide) nanosheets in solution or even inthe solid phase were performed. The resulting Co-LDH materials exhibitsuperior oxygen evolution reaction performance. This work has gooduniversality and provides potential value for crystal synthesis andresource recycling. Single-crystal-to-single-crystal (SCSC) transformationsprovidemore possibilities for phase transitions, which have attracted greatattention in crystal engineering. In this paper, we report a seriesof reversible SCSC transformations between nanoscale two-dimensionallayered double hydroxide (LDH) crystals and three-dimensional metal-organicframework crystals. They can proceed not only in solution systemsbut also on the surface of solid-state polyacrylonitrile films andfibers. Specifically, reversible SCSC transformations can be carriedout between nanoscale ZIF-67 and Co-LDH. The Co-LDH nanomaterialsdisplayed excellent oxygen evolution reaction performance. This workhas good universality and scalability, which provides a novel avenuefor the synthesis of crystal materials and is of great significancefor the recycling of resources.