Use of a vanadium nanostructured material for hydrogen peroxide electrogeneration

This paper reports the use of different proportions of vanadium nanostructured electrocatalysts for H2O2 electrogeneration. A comparative study using different mass proportions of vanadium (1%, 6%, 12%, 15% and 20%) was performed to produce H2O2. The V/C materials were prepared by a modified polymeric precursor method (PPM) and characterized by X-ray diffraction and transmission electron microscopy (TEM) analysis. XRD results identified different phases comprising V2O5 and VO2 while TEM micrographs show the vanadium nanoparticles in the range of 1-3 nm. The rotating ring-disk electrode (RRDE) technique was used to evaluate the kinetics of the oxygen reduction reaction (ORR). The results showed that the 12% V/C prepared by the PPM was the best composite among those investigated for the production of H2O2 in a 1 mol L-1 NaOH electrolyte solution because this electrocatalyst exhibited a H2O2 conversion efficiency of 68%. The ring current obtained with 12% V/C was greater than the obtained with Vulcan carbon, which was used as a reference material for H2O2 production and exhibited an efficiency of 31%. After the study with the RRDE, gas-diffusion electrodes (GDEs) containing the catalyst were used to evaluate the amount of H2O2 produced during exhaustive electrolysis. On the basis of these results, the 12% V/C GDE produced 620 mg L-1 of H2O2 in alkaline media, whereas the Vulcan carbon GDE produced only 369 mg L-1 at the same potential. In acidic media, the 12% V/C GDE produced 107 mg L-1 of H2O2, whereas Vulcan carbon produced only 72 mg L-1 at the same potential, indicating the better activity of V/C for H2O2 electrogeneration. The 12% V/C is composed primarily of the V2O5 phase, which shows acidic character that can increase the acidity of the surface, providing greater hydrophilicity and, consequently, greater activity toward the ORR via two-electron transference. (c) 2014 Elsevier B.V. All rights reserved.