Catalytic decomposition of H2O2 over a Au/carbon catalyst: A dual intermediate model for the generation of hydroxyl radicals

The generation of hydroxyl radicals (HO center dot) by H2O2 decomposition over solid catalysts (a Fenton-like reaction) will play an important role in the design of new processes for water treatment. More specifically, the understanding of H2O2 decomposition on Au nanoparticles (NPs) is crucial for the optimization of the structure of active sites and the evaluation of cytotoxicity of Au NPs. Here, the kinetic behavior of H2O2 decomposition over supported Au NPs was investigated in a buffer solution at pH similar to 6.8. Over a range of H2O2 concentrations, the decay of H2O2 followed a pseudo-first-order kinetic rate law with an apparent activation energy of 142 kJ/mol. The observed rate constant was linearly increased from (3.0 +/- 1.0) x 10(-3) to (66.7 +/- 2.3) x 10(-3) min(-1) with the increase in the Au NPs concentration. Further increase in the surface concentration of H2O2 may reduce the HO center dot generation efficiency. A dual intermediate model was proposed for the generation mechanism of HO center dot. (C) 2016 Elsevier Inc. All rights reserved.