Direct Visualization of Atomic Structure in Multivariate Metal-Organic Frameworks (MOFs) for Guiding Electrocatalysts Design

The direct utilization of metal-organic frameworks (MOFs) for electrocatalytic oxygen evolution reaction (OER) has attracted increasing interests. Herein, we employ the low-dose integrated differential phase contrast-scanning transmission electron microscopy (iDPC-STEM) technique to visualize the atomic structure of multivariate MOFs (MTV-MOFs) for guiding the structural design of bulk MOFs for efficient OER. The iDPC-STEM images revealed that incorporating Fe3+ or 2-aminoterephthalate (ATA) into Ni-BDC (BDC: benzenedicarboxylate) can introduce inhomogeneous lattice strain that weaken the coordination bonds, which can be selectively cleaved via a mild heat treatment to simultaneously generate coordinatively unsaturated metal sites, conductive Ni@C and hierarchical porous structure. Thus, excellent OER activity with current densities of 10 and 100 mA cm(-2) are achieved over the defective MOFs at small overpotentials of 286 mV and 365 mV, respectively, which is superior to the commercial RuO2 catalyst and most of the bulk MOFs.

Automated summary

The atomic structure of multivariate metal-organic frameworks (MTV-MOFs) was visualized using the iDPC-STEM technique, guiding the design of bulk MOFs for efficient oxygen evolution reaction (OER). Incorporating Fe3+ or 2-aminoterephthalate (ATA) into Ni-BDC weakened the coordination bonds, allowing for selective cleavage via mild heat treatment to generate coordinatively unsaturated metal sites, conductive Ni@C, and hierarchical porous structure. The defective MOFs exhibited excellent OER activity, with current densities of 10 and 100 mA cm(-2) achieved at small overpotentials of 286 mV and 365 mV, respectively, surpassing commercial RuO2 catalyst and most bulk MOFs.