Metal-Organic Framework Hexagonal Nanoplates: Bottom-up Synthesis, Topotactic Transformation, and Efficient Oxygen Evolution Reaction

Abstract

Rational design and bottom-up synthesis based on the structural topology is a promising way to obtain two-dimensional metal-organic frameworks (2D MOFs) in well-defined geometric morphology. Herein, a topology-guided bottom-up synthesis of a novel hexagonal 2D MOF nanoplate is realized. The hexagonal channels constructed via the distorted (3,4)-connected Ni₂(BDC)₂(DABCO) (BDC = 1,4-benzenedicarboxylic acid, DABCO = 1,4-diazabicyclo[2.2.2]octane) framework serve as the template for the specifically designed morphology. Under the inhibition and modulation of pyridine through a substitution-suppression process, the morphology can be modified from hexagonal nanorods to nanodisks and to nanoplates with controllable thickness tuned by the dosage of pyridine. Subsequent pyrolysis treatment converts the nanoplates into a N-doped Ni@carbon electrocatalyst, which exhibits a small overpotential as low as 307 mV at a current density of 10 mA cm^-2 in the oxygen evolution reaction.