Pd-decorated three-dimensional nanoporous Au/Ni foam composite electrodes for H₂O₂ reduction

Nanoporous gold (NPG) films were fabricated on Ni foam substrates via a two-step procedure which involves electrodeposition of Au-Sn alloy films on the Ni foam surface, followed by selectively leaching the Sn component through a chemical dealloying process. Pd nanoparticles were then electrochemically deposited on the NPG/Ni foam electrode. The morphology of the Pd-decorated NPG/Ni foam composite electrode (Pd@NPG/Ni foam) was characterized by scanning electron microscopy (SEM). The catalytic activity of the Pd@NPG/Ni foam composite electrode toward H₂O₂ electroreduction in acid media was evaluated by means of linear scan voltammetry and chronoamperometry. The Pd@NPG/Ni foam composite electrode exhibited high activity and excellent stability for the H₂O₂ electroreduction, generating a current density of 178 mA cm^-2 at 0 V in a 0.5 M H₂SO₄ + 0.6 M H₂O₂ electrolyte, in comparison to 98 mA cm^-2 on the Pd@Ni foam electrode and 36 mA cm^-2 on the NPG/Ni foam electrode. The developed three-dimensional (3D) hierarchical porous Pd@NPG/Ni foam can therefore be considered as a promising type of electrode for fuel cell applications.