▎ 摘　　要

The use of electrogenerated H2O2 in wastewater treatment is a promising method to degrade the potentially hazardous organic contaminants. Hydrothermally prepared nanocomposites of Nb2O5 nanoparticles on reduced graphene oxide (rGO) were tested toward the oxygen reduction reaction (ORR), via the production of H2O2. The Nb2O5-rGO composite shifts the onset potential to less negatives values when compared to unmodified rGO and Printex 6L carbon. Moreover, an increase in H2O2 production in acidic media from 73.7% to 85.3% was observed for rGO and Nb2O5-rGO, respectively. Nonetheless, the activity of both catalysts in alkaline medium is not significantly different. When compared to carbon Printex, the standard for this type of reaction, the Nb2O5-rGO electrode gives higher yields of H2O2 in either acidic (70.5% vs. 85.3%) or alkaline media (63.4% vs. 74.9%). The selectivity of Nb2O5-rGO composite toward H2O2 formation is attributed to the synergistic effect between the Nb2O5 nanoparticles and the rGO sheets. (C) 2015 Elsevier Inc. All rights reserved.