Silica nanosphere supported palladium nanoparticles encapsulated with graphene: High-performance electrocatalysts for methanol oxidation reaction

A new type of silica nanosphere supported palladium nanoparticles encapsulated with graphene (denoted as Pd/SiO2@RGO) sandwich nanostructure electrocatalyst is prepared via a two-step reduction method for the first time. The characterization of electrocatalyst morphology and composition is discussed by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The TEM and XRD results show that palladium nanoparticles (Pd NPs) with a narrow size distribution are uniformly dispersed between silica sphere and the graphene layer. The ternary hybrid electrocatalyst exhibits high activity (1533 mA mg(pd)(-1)), superior operational durability and anti-poisoning ability (I-f/I-b = 3.9) compared with other controlled Pd catalysts. Moreover, it significantly reduces the peak potential (ca. 40 mv) and onset potential (ca. 80 mv) than commercial Pd/C, accounting for combination of the merits of SiO2 nanosphere support and the excellent electronic conductivity of RGO while overcoming their shortcomings. We provide an efficient way to fabricate a promising non-platinum anode catalyst for alkaline fuel cells. (C) 2018 Elsevier B.V. All rights reserved.