Structural Reconstruction of a New Cobalt-Based Metal-Organic Framework for the Efficient Electrocatalytic Hydrogen Production.

Abstract

This study illustrates the fate of a cobalt-based metal-organic framework (CoL1-MOF) during the hydrogen evolution reaction in 1 M aqueous KOH. The electrocatalytic hydrogen evolution activity of a CoL1-MOF is evaluated using cyclic voltammetry (CV) in 1 M KOH, with a three-electrode setup under an N₂ atmosphere. The CoL1-MOF exhibits a 436 mV overpotential to reach a current density of 10 mA cm^{- 2} for hydrogen evolution reaction (HER), while the bare GCE shows negligible activity. Tafel slope of 75 mV dec^-1 reveals that CoL1-MOF follows the Volmer-Heyrovsky mechanism. The intrinsic activity of CoL1-MOF is further assessed through electrochemical parameters, including electrochemical double-layer capacitance (C_dl), roughness factor (R_f), and electrochemically active surface area (ECSA), demonstrating enhanced accessibility to active sites. Stability tests show that CoL1-MOF maintains consistent HER activity during continuous operation, with a gradual increase in current density due to structural reconstruction. Postelectrolysis analysis such as Powder X-ray Diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), Fourier Transformed Infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Energy Dispersive Analysis of X-rays (EDAX) confirmed the formation of metal hydroxide/oxyhydroxide phases accompanied by morphological changes. Remarkably, the post-electrolysis CoL1-MOF demonstrated enhanced HER performance with a reduction in overpotential. This study demonstrates the cost-effective synthesis of 1D transition metal-based MOFs and their potential for sustainable hydrogen production, offering a promising solution to the energy crisis.