Nitrogen-doped graphene supported highly dispersed palladium-lead nanoparticles for synergetic enhancement of ethanol electrooxidation in alkaline medium

Highlights: • A novel N-doped graphene supported PdPb nanocatalyst was prepared. • N-doped graphene facilitates more uniform dispersion of metal particles than graphene. • Current for ethanol oxidation of PdPb/NG (152.3 mA cm⁻²) is 4 times higher than Pd/G. • PdPb/NG catalyst shows excellent catalytic durability among the catalysts. • Catalytic performance was enhanced by the bifunctional mechanism and electronic effect. - Abstract: In this work, a series of palladium and palladium-lead nanoparticles supported on active carbon, graphene and nitrogen-doped graphene are synthesized via a one-step reduction method. Atomic absorption spectroscopy, X-ray powder diffraction, transmission electron microscope and X-ray photoelectron spectroscopy are used to characterize the catalysts. The results indicate that metal nanoparticles are more uniformly dispersed on the surface of N-doped graphene than those on graphene, without any aggregation. Various electrochemical techniques are carried out to evaluate the electrocatalytic ethanol oxidation activity and durability. The peak current for ethanol electrooxidation of Pd/N-doped graphene increases to 70.2 mA cm⁻², obviously higher than that of Pd/Graphene (38.0 mA cm⁻²) and even surpasses that of Pd/C (51.9 mA cm⁻²). N-doped graphene support not only possesses faster dehydrogenation but provides an electron effect to Pd. Introduction of Pb into the catalyst causes the formation of abundant oxygenated species on the catalyst surface at low potential. Based on the synergistic effect of N and Pb towards Pd particles, the PdPb/N-doped graphene catalyst (Pd:Pb = 8:1.0) exhibits remarkably enhanced activity up to 152.3 mA cm⁻² for ethanol oxidation, which is 4.0 and 2.9 times higher than that of Pd/Graphene and Pd/C, respectively. The catalytic durability and stability are also greatly improved