Synthesis of palladium nanoparticles supported on reduced graphene oxide-tungsten carbide composite and the investigation of its performance for electrooxidation of formic acid

Abstract

Palladium (Pd) nanoparticles are uniformly distributed on tungsten carbide (WC)-reduced graphene (RGO) oxide composite to synthesize a new electrocatalyst Pd-WC/RGO. The catalysts prepared with various amounts of tungsten carbide are characterized by transmission electron microscopy, energy dispersive spectrometry, and X-ray diffraction. The electrocatalytic performance of the prepared materials toward formic acid oxidation reaction is tested to evaluate the effect of adding WC. The results show that Pd-WC/RGO electrocatalyst with a 25 wt% WC (Pd-WC(25)/RGO) presented a narrow Pd particle size distribution both on the surface of RGO and WC nanocrystallites. Its current density of the positive main anodic peak of formic acid electrooxidation is up to 42.35 mA cm−2. Compared with the other catalysts, especially the Pd/RGO, the Pd-WC(25)/RGO demonstrate better electrocatalytic activity and higher stability toward the formic acid oxidation reaction. It is attributed to the small size and uniform dispersion of Pd NPs on both RGO sheets and WC nanocrystallines, and to the stronger synergistic effect between Pd NPs and WC nanocrystallines, which result from the proper mass percentage of 25 % WC in the Pd-WC(25)/RGO composite. The present work reveals that WC could be a good additive component, and the composite WC/RGO could be a better support in preparing Pd-based catalysts.