Decorated fractal Ni-Cu foam with Pd nanoparticles as a high-performance electrocatalyst toward hydrogen evolution reaction

Abstract

• The Ni-Cu foam was decorated with Pd nanoparticles by galvanic replacement method. • The Tafel slope of Ni-Cu/Pd is 72 mV dec −1 which is 94 mV dec −1 less than substrate. • The fractal architecture of Ni-Cu/Pd provided a high surface area (112.5 cm 2 ). • Ni-Cu/Pd requires 134 mV overpotential at the current density of 10 mA cm −2 . Fractal Ni-Cu foam with palladium nanoparticles on (Ni-Cu foam / Pd) was prepared by electrodeposition and galvanic replacement method. The results showed that after the fabrication of Pd particles on Ni-Cu foam, the hydrogen evolution reaction (HER) activity of the electrode improved dramatically. The morphology and phase structure of deposited layers were studied by field emission scanning electron microscopy, and X-ray diffraction methods, respectively. In order to investigate the morphology of the coatings in more details, transmission electron microscope was used, which its figures authenticated the presence of Pd nanoparticles on the fractal structures of Ni-Cu. Based on the electrochemical tests in KOH (1.0 M), the Ni-Cu foam / Pd electrode has good electrocatalytic properties, with a low overpotential of 134 mV at 10 mA cm −2 and Tafel slope of 72 mV dec −1 . Cyclic voltammetry measurements showed that the Ni-Cu foam/Pd possesses a high electrochemical surface area of 112.5 cm 2 that was attributed to the presence of both fractal Ni-Cu foam and Pd nanoparticles. Overall, this study proposes a feasible approach for the fabrication of a highly-porous, super hydrophilic, and scalable electrode with a great performance toward HER.