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 ) by H 2 O 2 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 H 2 O 2 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 H 2 O 2 decomposition over supported Au NPs was investigated in a buffer solution at pH ∼ 6.8. Over a range of H 2 O 2 concentrations, the decay of H 2 O 2 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) × 10 −3 to (66.7 ± 2.3) × 10 −3 min −1 with the increase in the Au NPs concentration. Further increase in the surface concentration of H 2 O 2 may reduce the HO generation efficiency. A dual intermediate model was proposed for the generation mechanism of HO . [ABSTRACT FROM AUTHOR]