Pd catalyst supported on a chitosan-functionalized large-area 3D reduced graphene oxide for formic acid electrooxidation reaction

A large-area three-dimensional (3D) reduced graphene oxide (TRGO) material was obtained by facile heat treatment of a two-dimensional (2D) reduced graphene oxide (RGO) material. X-ray diffraction (XRD), scanning electron microscopy (SEM) and nitrogen adsorption results reveal that the new material is composed of small and fluffy graphene nanosheets, with many graphene arrays as well as 3D interconnected macropores and mesopores in some local positions, and possesses an ultrahigh specific surface area (>1000 m2 g−1) and large pore volume. The material was used to support a Pd catalyst for formic acid electrooxidation, demonstrating a much better electrocatalytic activity in terms of the onset potential and peak current density (seven times larger) than that of conventional carbon black, the most popular catalyst support. To tailor the electronic properties, the TRGO material was further functionalized with chitosan (CS). Compared to the Pd loaded on TRGO, Pd nanoparticles supported on the CS-functionalized TRGO show a better catalytic activity and good stability. This work provides a promising catalyst support material for direct formic acid fuel cells.