Influence of the structural and surface characteristics of activated carbon on the catalytic decomposition of hydrogen peroxide

Hydrogen peroxide decomposition has been studied with three activated carbons before and after different modifications upon HCl lixiviation, oxidation with HNO3 and heat treatment in inert atmosphere. The surface of activated carbon promotes H2O2 decomposition to an extent depending on related-structural features and the amount and nature of surface oxygen groups. A lower ordering of the carbon structure with less developed graphene layers leads to a higher decomposition rate due to a higher surface concentration of unpaired electron active sites. In activated carbons with a similar structural ordering, the presence of acidic surface oxygen groups inhibits the decomposition of hydrogen peroxide. Taking into account these two phenomena, empirical equations based on the most reactive carbon fraction by TPO, defects aliphatic carbon fraction, assessed by XPS, and the content of surface oxygen groups, determined by TPD, have been developed for describing the hydrogen peroxide decomposition ability of activated carbons.

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► AC structural order and surface oxygen groups affect the H2O2 decomposition.
► A lower ordering of the carbon structure leads to a higher decomposition rate.
► At similar structural ordering the reaction rate decreases due to the oxygen groups.
► These effects have been modelled by means of TPO, TPD and XPS analyses.