Engineering the coordination mode of atom or ion onto the substrate remains challenging.

Guided by theoretical calculation, Dr. WANG Tie's group from the Institute of Chemistry of the Chinese Academy of Sciences, LIN Zhenyu's group from Fuzhou University, and the collaborators, reported their success in preparing stacked-nanosheet metal–organic frameworks (MOFs-CASFZU-1) based catalyst with precisely controlled coordination sites on the surface and enhanced catalytic reactivity and structural robustness. The study was published in Nature Communications

Monodispersed single atoms and ions on solid substrates, as unsaturated coordinated metal sites, have exhibited excellent catalytic activity. However, it is rarely reported in systematically tuning coordination modes and establishing the exact structure-to-property correlation in coordinatively unsaturated metal atoms for catalysis.

The researchers took inspiration from the hexagonal-shaped cells of a honeycomb, which provide relatively high out-of-plane compression and shear properties, and developed an etching strategy for preparation of CASFZU-1 with three-coordinated copper (Cu) by selectively etching the classical MOF-HKUST-1 along the (111) facets.

The highly active three-coordinated Cu sites were effective for important cycloaddition reaction of CO₂, inducing activity markedly exceeding the maximum values of previous reported catalysts, especially under industrially favoured conditions of non-energy consumption.

The CASFZU-1 heterogeneous catalyst could maintain undiminished activity in marked contrast to the nanosheet catalyst that typically suffers from fragmentation and aggregation to form large unreactive species that prevent continuity of the reaction.

This study forms a basis for the rational design and construction of highly efficient and robust catalysts in the field of single-atom or ion catalysis.

 Illustration of etching strategy for preparation of CASFZU-1. (Image by Dr. HUANG Chuanhui)