Polymer-assisted formation of 3D Pd nanoassemblies: highly active catalysts for formic acid electrooxidation

Abstract

Three-dimensional (3D) Pd nanoassemblies were synthesized by a facile hydrothermal procedure, in which polyallylamine hydrochloride (PAH) was simultaneously used as a cross-linking and scaffold molecule in order to construct the 3D interconnected nanoassemblies. The formation process and mechanism of the Pd nanoassemblies were investigated using temporal TEM images. XRD was used to probe their crystal structure, which showed a clear appearance of metallic nanocrystallites with high index crystal facets. XPS was conducted to study surface elemental composition, which confirmed the physical and chemical integration of Pd and PAH. Finally, the 3D Pd nanoassemblies were used as catalysts for formic acid electro-oxidation. Compared to Pd bulk produced without PAH and commercial Pd black, the Pd nanostructure assemblies towards the electro-oxidation of formic acid exhibited higher electrochemical activity. This behavior is mainly due to their porous structure, high specific surface area which offers more catalytic sites, and their sufficient cavity space which enables facile charge transport of electrochemical reactions.