Enhanced oxygen evolution catalyzed by in situ formed Fe-doped Ni oxyhydroxides in carbon nanotubes

The rational design and preparation of cost-effective, efficient and durable metal carbon nanomaterials for the oxygen evolution reaction (OER) is of great urgency. Herein, we report a high-performance OER electrocatalyst consisting of bimetallic FeNi₃ nanoparticles encapsulated in hierarchical carbon nanomaterial, denoted as FeNi3@NCNT. Through a stepwise strategy, hollow carbon nanorods with abundant carbon nanotubes can be successfully calcined from rod-like NiOF-1-Fe, which are hydrolyzed to the initial NiOF-1 by Fe(III) ions. The optimal FeNi₃@NCNT catalyst exhibits an excellent electrochemical performance with a low overpotential of 264 mV at 10 mA cm⁻², a Tafel slope of 58.5 mV dec⁻¹, and a robust stability over 10 hours compared to the control samples. This enhanced OER arises from the unique hollow nanorod modified with a nanotube structure, a large surface area, a rich nitrogen content, and the synergistic effect between Ni and Fe species. Indeed, it is catalyzed by in situ generated Fe coupling with NiOOH in carbon nanotubes, which is validated by the subsequent theoretical calculations. This work enables insights into the mechanism of Fe-doped Ni oxyhydroxides for efficient OER and adds to the increasing understanding of the design and synthesis of novel catalysts for efficient energy conversion and storage.