Sulfur-Doped Graphene-Supported Nickel-Core Palladium-Shell Nanoparticles as Efficient Oxygen Reduction and Methanol Oxidation Electrocatalyst

Abstract

The design of novel platinum-free highly efficient electrocatalysts for the oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) has been regarded as the core challenge toward the development of commercially available fuel cell devices. In this contribution, a facile strategy was applied to prepare surfactant-free nickel-core palladium-shell nanoparticles, abbreviated as Pd@NiNPs, uniformly distributed on sulfur-doped graphene (SG). The Pd@NiNPs/SG hybrid material was realized by employing a modified polyol method for the in-situ preparation of NiNPs/SG, followed by deposition of a Pd shell through the galvanic replacement method and complementary characterized by Raman and IR spectroscopy, STEM/EELS, SEM and EDS as well as XRD and TGA. The Pd-to-Ni molar ratio was optimized in view of the hybrid’s electrocatalytic performance. Interestingly, the Pd@NiNPs/SG hybrid was proved to be a highly efficient and stable electrocatalyst towards ORR and MOR. It exhibited comparable initial ORR perfo...