Flocculation-induced homolysis of hydrogen peroxide in aqueous colloid solution of titanium dioxide nanoparticles

Thermal generation of oxygen and hydroxylated aromatic compounds by hydrogen peroxide, catalyzed by flocculation of titanium dioxide nanocrystallites aqueous suspension upon addition of hydrogen peroxide, is reported. The oxidation involves catalytic cleavage of a peroxide molecule followed by hydroxyl reaction with the organic solutes. The catalytic hydroxylation is associated with formation of TiO₂-H ₂O₂ aggregates, which occurs within a specific range of [TiO₂]/[H₂O₂] ratio. Comparison of the activation energy to literature values in the absence of nanoparticles indicates that flocculation induces an increase of the rate without decreasing the activation energy. This is, to the best of our knowledge, a unique case of nanoparticles catalysis driven by formation of a three-dimensional structure of the suspended particles.