Electro-Fenton degradation of Rhodamine B with in-situ H2O2 generation by Au nanoparticles modified reduced graphene oxide

AuNPs/rGO composite cathode was prepared using in-situ reduction method and was applied for H 2 O 2 generation through molecular oxygen (O 2 ) undergoing a 2-electron reduction reaction in the electro-Fenton system. The results showed the AuNPs/rGO cathode exhibited good activity and stability. The size and loading amount of AuNPs, as well as applied voltages were considered for evaluating the catalytic activity of AuNPs/rGO cathode. AuNPs 2:1 /rGO with the smallest size (2.8 ± 0.6 nm) exhibited higher catalytic activity in the electro-Fenton system when the AuNPs 2:1 loading amount was 2.7 %, pH= 3, and applied voltage was −0.6 V (vs. SCE), resulting in an H 2 O 2 yield of 19.3 ± 0.1 mmol g −1 . The synergistic effect of AuNPs 2:1 and rGO enhanced the activation of H 2 O 2 , generating a large number of hydroxyl radicals (∙OH) for efficient degradation of rhodamine B (RhB), corresponding to a degradation efficiency of 100 % within 30 min. In addition, AuNPs 2:1 /rGO exhibited excellent stability and reusability in cyclic experiments. The quenching experiment and the radical spin trap test showed ∙OH and superoxide anion (∙O 2 ̄) as the active species during the reaction process. Furthermore, LC-MS and in-situ FTIR were used to analyze the intermediate products of the degradation process and determine the reaction mechanism.