Carbon nanotube/metal organic framework hybrid scaffolds for scalable and self-structured OER catalyst coating: From rheology study to MEA fabrication

• A scalable catalyst coating method was developed using FeNi-MOF particles and an FCNT hydrogel. • Uniform dispersion of MOF on FCNT scaffolds increased active site exposure and created a well-connected conductive structure. • During OER, the MOF transformed into a hybrid structure of metal hydroxides and organic materials, with FeNiOOH as the actual active site. • The catalyst demonstrated low overpotentials of 263 mV at 10 mA/cm 2 and 355 mV at 100 mA/cm 2 in half-cell tests. • In AEMWE, the system achieved 1.8 V at 1 A/cm 2 , outperforming IrO x /Nafion_CC by 0.69 V at a loading of 0.2 mg/cm 2 . We developed a scalable binder-free composite electrode layer fabrication method by integrating Fe-Ni-based MIL-101 MOF catalysts for the oxygen evolution reaction (OER) with carbon nanotube (CNT) scaffolds. This synergy significantly enhanced active site exposure, as the MOF uniformly dispersed across the CNT surface, forming a 3D electroconductive structure. In particular, the MOFs are further transformed into the hybrid structure of metal hydroxide and organic compounds during OER conditions, leading to an enhanced and stable catalytic layer. The resulting electrode exhibited improved catalytic performance, with overpotentials of 263 mV at 10 mA/cm 2 and 355 mV at 100 mA/cm 2 in half-cell tests. In an alkaline exchange membrane water electrolyzer (AEMWE), the electrode achieved a voltage of 1.8 V at 1 A/cm 2 , with an overpotential 0.69 V lower than that of the conventional IrO x /Nafion_CC electrode at a loading of 0.2 mg cm −2 . Our method effectively overcomes the scalability challenges associated with traditional catalyst growth strategies and demonstrates that MOF materials can function as electrocatalysts without further treatment.