The development of efficient, durable, cost-effective, and scalable electrocatalysts for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is essential for advancing water-splitting technologies in sustainable energy systems. In this work, we report the synthesis of a Sn-doped NiFe layered double hydroxide (LDH)/carbon nanotube (CNT) composite as a bifunctional electrocatalyst, with particular emphasis on its OER activity. The Sn-NiFe LDH was synthesized via a simple co-precipitation method, followed by its integration with CNTs using a wet impregnation approach.

Comprehensive characterizations were performed using X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). Electrochemical properties were investigated in 1 M KOH using linear sweep voltammetry (LSV), cyclic voltammetry (CV), electrochemical active surface area (ECSA), electrochemical impedance spectroscopy (EIS), and Tafel slope analysis.

The optimized Sn-NiFe-4 LDH/CNTs electrocatalyst exhibited outstanding OER performance, achieving a low overpotential of 203 mV at 10 mA cm^-2 and a Tafel slope of 13 mV dec^-1. For HER, the material showed an overpotential of 488 mV at the same current density, with a Tafel slope of 104.07 mV dec^-1. These results highlight the potential of Sn-doped NiFe LDH/CNT composites as effective, durable, and scalable bifunctional electrocatalysts, paving the way for cost-efficient and scalable hydrogen production through overall water splitting.