Metal–Organic Framework-Derived NiS/Fe₃O₄ Heterostructure-Decorated Carbon Nanotubes as Highly Efficient and Durable Electrocatalysts for Oxygen Evolution Reaction

Because of the sluggish oxygen evolution kinetics, it is extremely important but still challenging to develop low-cost, efficient, and stable electrocatalysts for oxygen evolution reaction (OER) to enhance the efficiency of water electrolysis. Herein, for the first time, we present a novel heterostructure catalyst, constructed by ultrafine NiS/Fe₃O₄ heterostructural nanoparticles decorated on a carbon nanotube (CNT) matrix (NiS/Fe₃O₄ HNPs@CNT), which is synthesized by a facile hydrothermal reaction and subsequent sulfurization process. The NiS/Fe₃O₄ HNPs@CNT hybrid delivers superior OER activity in alkaline medium: it delivers a current density of 10 mA cm^–2 at an ultralow overpotential of 243 mV with a small Tafel slope of 44.2 mV dec^–1, which outperforms the benchmark RuO₂ electrocatalyst; moreover, it exhibits terrific long-term stability over 36 h without any noticeable performance decay. The exceptional OER performance can be attributed to the unique nanoarchitecture, high conductivity of the CNT matrix, and particularly, the interaction between the Ni and Fe species in NiS/Fe₃O₄ heterostructural nanoparticles. This work introduces a sensible nanoarchitecture design with a facile and novel fabrication strategy to attain nonprecious metal-based composite catalysts with high OER performance and outstanding long-term stability.