Ni3S4/FeNi2S4 heterostructure-embedded metal-organic framework-derived nanosheets interconnected by carbon nanotubes for boosting oxygen evolution reaction

The efficiency of electrolytic water splitting is hampered by the slow kinetics of the oxygen evolution reaction (OER). Addressing this challenge, we present a novel catalyst with rich Ni3S4/FeNi2S4 heterostructures anchored metal-organic framework-derived nanosheets interconnected by carbon nanotubes (NiFe–S@CNT). The NiFe–S@CNT electrocatalyst shows an ultralow overpotential of 246 mV at a current density of 10 mA/cm2 (η10), surpassing the benchmark RuO2 (η10 = 291 mV) as well as many reported sulfide electrocatalysts. The strong heterointerface interaction between Ni3S4 and FeNi2S4 induce synergistic effects, modifying the electronic structure of active sites and generating a large number of lattice defects. Additionally, the carbon nanotubes skeleton facilitates efficient electron transfer and enhances electrical conductivity during the catalytic process. Moreover, the metal-organic framework derivative inherits a porous structure, aiding in electrolyte penetration and efficient bubble release. This study provides a facile and scalable strategy to develop nonprecious transition-metal-based OER catalysts with abundant heterointerfaces and active sites for efficient water splitting.