Abstract:

We devised and fabricated a Pd/Ni(OH)₂ composite catalyst with low noble metal content that grows in situ on nickel foam (NF) using the hydrothermal synthesis method. The morphology and microstructure of the catalyst were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The hydrogen evolution performance of the composite catalyst was evaluated by linear scanning voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CP). The composite catalyst exhibited a special nanostructure consisting of an ultra-thin Ni(OH)₂ film growth on the surface of the nickel foam with palladium nanoparticles uniformly embedded in the Ni(OH)₂ thin film. The Ni(OH)₂ on the surface of the catalyst might considerably promote the dissociation of water and the formation of hydrogen intermediates (H_ad) that subsequently adsorbed on the nearby Pd and quickly recombined into hydrogen molecules. The composite catalyst exhibits a synergistic effect for the hydrogen evolution reaction (HER), which might decrease the over-potential of hydrogen evolution and enhance the activity of the hydrogen evolution reaction. Growing the composite catalyst in situ on the nickel foam effectively improved the stability of the catalyst for the HER in alkaline solutions.

Key words: Difunctional system, Hydrogen evolution reaction, Electrolysis of water, Composite catalyst, Nickel hydroxide