Ligand-induced hollow binary metal-organic framework derived Fe-doped cobalt-carbon nanomaterials for oxygen...

There is significant anticipation for high-efficiency and cost-effective non-precious metal-based catalysts to advance the industrial application of the anodic oxygen evolution reaction (OER) for hydrogen production. This study introduces an efficient strategy that utilizes ligand-induced metal-organic framework (MOF) building blocks for the synthesis of hollow binary zeolitic imidazolate frameworks 67 (ZIF-67) and Prussian blue analogues (PBAs) (ZIF-67@PBA) heterostructures through a hybrid MOF-on-MOF approach. Manipulating the Co²⁺/Zn²⁺ ratio in the precursor ZIF-67 allows for the convenient synthesis of the final product, denoted as Co_xFe-ZP, after pyrolysis, where the inclusion of Zn effectively modulates the distribution of Co in the catalyst. The resulting Co_xFe-ZP catalysts exhibit a positive synergistic effect between hollow graphitic carbon nanomaterials and Fe-doped Co nanoparticles. The optimal Co_0.3Fe-ZP catalyst demonstrates satisfactory OER performance, achieving an overpotential of 302 mV at 10 mA cm^-2 and a small Tafel slope of 60.0 mV dec^-1. Further analysis of the activation energy confirms that the enhanced OER activity of Co_0.3Fe-ZP can be reasonably attributed to the combined influence of its morphology and composition. This study demonstrates a ligand-induced method for examining the morphology and electrochemical properties of grown binary MOF-on-MOF heterostructures for OER applications.