Hydrothermally Fabricated NiO@TiO₂–Nanofiber Composite for Efficient Electrocatalytic Hydrogen Evolution Reaction

Abstract

Nowadays, hydrogen fuel is becoming more popular, and it is attracting significant attention as a sustainable and environmentally benign energy source owing to its zero emission of harmful substances and high energy density. Hydrogen generation through the electrocatalytic hydrogen evolution reaction (HER) employs economically inexpensive and selfsupported electrocatalysts that hold immense potential to provide a sustainable and cost-effective fuel in the future energy scenario. A self-supported NiO@TiO 2 nanofiber composite on Ti-foil is synthesized via a hydrothermal approach, and it is used as an electrocatalyst in the HER under alkaline conditions. The surface morphology, crystalline structure, and chemical composition of the electrode are analyzed by using high-resolution scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, which confirms that NiO nanoparticles are anchored to the surface of TiO 2 nanofibers. Investigation of the electrocatalytic properties of the NiO@TiO 2 nanofiber composite in a 1 M KOH electrolyte solution for the HER showed an overpotential of 144 mV at 10 mA cm −2 with a Tafel slope of 152.34 mV dec −1 . The NiO that is anchored to the TiO 2 nanofibers creates more catalytically active sites, which increases the surface area and enhances the HER performance. The charge transfer resistance of R ct = 41.6 Ω is determined from the electrode kinetics analyzed by using an electrochemical impedance spectroscopy Nyquist plot. The chronopotentiometric stability test confirms that the NiO@TiO 2 composite electrode shows a robust production of H 2 gas with only 7.6% potential deviation after 12 h of electrocatalytic activity. Furthermore, a Faradaic efficiency of 86% for hydrogen is achieved after 100 min of the HER. The results confirm that the NiO@TiO 2 nanofiber composite is a promising candidate material for the electrocatalysis of the HER.