Multi-walled carbon nanotube-supported Ni@Pd core–shell electrocatalyst for direct formate fuel cells

Abstract

In the present work, Ni@Pd core–shell nanoparticles are successfully deposited on multi-walled carbon nanotubes as support and investigated their performance towards formate oxidation reaction. The structural features of the catalyst are characterized by scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. According to the results, the size of the Ni@Pd core–shell nanoparticles is 5–10 nm and the nanoparticles are uniformly deposited on the multi-walled carbon nanotubes. The performance of the synthesized electrocatalysts for the formate oxidation reaction is investigated by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy as well as their comparison with Ni–Pd alloy nanoparticles on multi-walled carbon nanotubes. The results indicated that the Ni@Pd core–shell nanoparticles on multi-walled carbon nanotubes show higher electrocatalytic activity and stability than the Ni–Pd alloy nanoparticles on multi-walled carbon nanotubes against formate electrooxidation reaction. Moreover, the efficiency of synthesized anodic electrocatalysts is evaluated in a direct sodium formate-hydrogen peroxide fuel cell by employing a Pt/carbon as cathode (0.5 mg cm⁻²) and Ni@Pd core–shell nanoparticles on multi-walled carbon nanotubes as anode (1 mg cm⁻²). A maximum power density of 45.56 mW cm⁻² at 25 °C is achieved for this measurement.