Use of a vanadium nanostructured material for hydrogen peroxide electrogeneration

Abstract This paper reports the use of different proportions of vanadium nanostructured electrocatalysts for H 2 O 2 electrogeneration. A comparative study using different mass proportions of vanadium (1%, 6%, 12%, 15% and 20%) was performed to produce H 2 O 2 . 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 V 2 O 5 and VO 2 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 H 2 O 2 in a 1 mol L −1 NaOH electrolyte solution because this electrocatalyst exhibited a H 2 O 2 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 H 2 O 2 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 H 2 O 2 produced during exhaustive electrolysis. On the basis of these results, the 12% V/C GDE produced 620 mg L −1 of H 2 O 2 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 H 2 O 2 , whereas Vulcan carbon produced only 72 mg L −1 at the same potential, indicating the better activity of V/C for H 2 O 2 electrogeneration. The 12% V/C is composed primarily of the V 2 O 5 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.