Experimental and theoretical studies of WO3/Vulcan XC-72 electrocatalyst enhanced H2O2yield ORR performed in acid and alkaline medium

The oxygen reduction reaction (ORR) plays a pivotal role in clean energy generation and sustainable chemical production, particularly in the synthesis of hydrogen peroxide (H2O2). In this study, WO3/Vulcan-XC72 electrocatalysts have been synthesized and characterized for ORR applications. We assessed the ratio of WO3to Vulcan-XC72 and investigated the impact of electrolytes pH (covering acidic and alkaline media) on the ORR process. The results revealed that WO3with a monoclinic crystalline phase and nanoflower-like morphology was successfully synthesized, and confirmed an improvement in surface properties, with an increase in hydrophilicity and superficial oxygenated species. Electrochemical studies showed that WO3/C was the most selective for H2O2electrogeneration, compared to pure Vulcan-XC72, in both acidic and alkaline media. These results indicate that the ORR on the WO3/C electrocatalyst surface has a pH-dependent mechanism. Using WO3/C GDEs, an accumulation of 862 mg L-1of H2O2was achieved after 120 min of electrolysis at 100 mA cm-2. The higher selectivity of WO3/C could be related to the presence of more oxygen functional acid species on the catalyst surface and increased hydrophilicity compared to pure Vulcan, as well as a synergistic effect of the WO3nanoflowers in ORR, confirmed by theoretical calculations. The results reveal that WO3/Vulcan is a promising catalyst for H2O2electrogeneration via the ORR.