Fabrication of 0D/2D CoFe₂O₄/CoFe LDH composite intruded within CNTs network as a high-performance electrocatalyst for oxygen evolution and hydrogen evolution reactions

Designing highly efficient and durable multicomponent heterostructured composites as catalytic materials for concomitant hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is highly desirable. Researchers all over the world are continuously working to develop such materials. Herein, CNTs wrapped CoFe₂O₄/CoFe LDH (CoF/CoFe LDH@CNTs) ternary composite is synthesized by hydrothermal and ultra-sonication routes. Numerous methods, including X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), electrical Mott-Schottky, and electrochemical impedance spectroscopy (EIS) are employed to study structure, morphology, flat band potential, and electrochemical properties of prepared samples. In terms of water splitting performance, CoF/CoFe LDH@CNTs composite showed predominant performance for both HER and OER activities, as compared to its analogs (CoF and CoF/CoFe LDH). Faster electron transfer is also exhibited by CoF/CoFe LDH@CNTs, as it possesses a lower Tafel slope. For OER, CoF/CoFe, LDH@CNTs require a small overpotential of 170 mV to reach a current density of 10 mA cm⁻² in 1 M KOH, with a Tafel slope of 42 mV dec^-1. Similarly, for HER an overpotential of 218 mV is required to drive 10 mA cm⁻² with a small Tafel slope of 31 mV dec^-1. Impedance studies show a small value of charge transfer resistance (R_ct = 1.11 Ω) for CoF/CoFe, LDH@CNTs. Significant electrochemical performance for CoF/CoFe, LDH@CNTs for both half-reactions (OER and HER) is ascribed to the synergy among electrochemically active CoF and CoFe LDH, and a highly conductive network of CNTs. The present strategy improves the electrochemical performance of electrochemical systems relevant to energy applications.