Rapid Electrodeposition of Defect-Tuned MOF Nanoarchitectures: Synergistic Unlocking Electrochemical Performance via...

Metal-organic frameworks (MOFs) are increasingly used in energy storage and the oxygen evolution reaction (OER), where surfaces of MOF typically undergo structural transformation into metal (oxy)hydroxides as the true active sites. Synthesizing ultrasmall or amorphous MOF nanoparticles enables precise activation over the structural reconstruction. This work rapidly and precisely tailors ultrafine and order-disorder structure in MOF-74 crystals using ligands 2,5-dihydroxyterephthalic acid (H₄dobdc) and competitive salicylic acid (SA) via electrodeposition. Electrodeposition rapidly produces nanofragment (2∼3 nm)-amorphous MOF(Co)-SA1. The introduction of a secondary nickel center electronically modulates the primary cobalt in MOF(Co₄Ni₁)-SA1. X-ray absorption fine structure (XAFS) spectroscopy confirms this structure, which facilitates a structural reconstruction. This reconstruction, evidenced in the redox region by in situ Raman spectra, results in superior performance and long stability for both energy storage and OER applications. Theoretical calculations reveal a reduced reaction energy barrier (from 1.59 to 0.50 eV) correlated with a smaller crystal size, and Ni promotes electron transfer between Co and ligands and lowing the potential of redox of Co. Thus, rapid electrodeposition combined with precise defect engineering within MOF crystals effectively tailors the crystal size, coordination environment of metal centers, and subsequent electrochemical reconstruction, offering a viable strategy for enhanced electrochemical applications.