Nitrogen-doped graphene/tungsten oxide microspheres as an electro-catalyst support for formic acid electro-oxidation

Tungsten trioxide (WO3) spheres decorated with nitrogen-doped graphene (NRGO-WO3) were synthesized by applying the spray-drying procedure and characterized for their ability to serve as an electro-catalyst support for formic acid electro-oxidation. A possible mechanism for the formation of NRGO-WO3 was proposed based on the results of tunneling electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Pd nanoparticles with dimensions of 4.8 nm were loaded onto the surface of NRGO-WO3 using a conventional sodium borohydride reduction method. The electrocatalytic performances of Pd/NRGO-WO3 for formic acid oxidation were investigated by using cyclic voltammetry and chronoamperometry. Due to the decrease in the resistance to electron transfer resulting from the modification of N-doped graphene, which produced an excellent electrical conductor, as well as due to the hydrogen spill-over effect, which accelerated the dehydrogenation of formic acid on Pd active sites, a great enhancement of the electrochemical performances was achieved.