Facile synthesis of a Ni–Cu composite reinforced with a para-phenylenediamine layer for enhanced hydrogen evolution reaction

Abstract

In the race to develop new catalysts for water splitting, researchers are increasingly focusing on the design of cost-effective materials, particularly first-row transition metals. Nickel and copper catalysts are promising candidates due to their low cost and excellent compatibility. Herein, for the first time, the electrochemical synthesis of Ni–Cu-based nanomaterials reinforced with a para-phenylenediamine (pPD) layer for the HER is reported. A very simple method involving the electrodeposition of a pPD layer on a carbon paste electrode (CPE), followed by the electrodeposition of Ni–Cu particles at a constant current to form Ni₄Cu₁/pPD/CPE, was employed. The morphological, structural and electrochemical properties of the catalyst were thoroughly characterized using several techniques such as field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The catalytic performance and stability of the catalyst were evaluated in a 1 M KOH solution using linear sweep voltammetry and chronoamperometry, respectively. The prepared Ni₄Cu₁/pPD/CPE electrocatalyst exhibited high activity toward HER in an alkaline medium, achieving a very low overpotential of −70 mV vs. RHE at 10 mA cm⁻² and a value of 87 mV dec⁻¹ for Tafel slope. The results indicate that the prepared Ni₄Cu₁/pPD/CPE electrocatalyst is a highly promising catalytic material for effective green hydrogen production.