Metal-Organic-Framework-Derived Cobalt nanoparticles encapsulated in Nitrogen-Doped carbon nanotubes on Ni foam integrated Electrode: Highly electroactive and durable catalysts for overall water splitting.

Abstract The rational design and use of highly efficient, economic, and environmentally friendly bifunctional catalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is important for developing methods for overall water splitting. Here, we report a facile self-catalyzed growth strategy for in situ encapsulation of Co nanoparticles with N-doped carbon nanotubes (NCNTs) on Ni foam (NF) (Co/NCNTs-NF-T; T represents the pyrolysis temperature). The zeolite imidazole framework (ZIF-67) precursor, which was used as a structure inducer, provided a Co source for catalyzing melamine graphitization and promoted in situ growth of NCNTs on the NF surface. This encapsulation structure and self-supporting system enhance the HER and OER activities of Co/NCNTs-NF-900 (low overpotentials of 66.98 mV for the HER and 240.32 mV for the OER at 10 mA cm−2). This binder-free catalyst for overall water splitting, i.e., Co/NCNTs-NF-900, has excellent catalytic activity and durability. This method offers a facile and green strategy for designing highly active bifunctional electrocatalysts and paves the way for the future development of energy conversion/storage systems.