Co3O4 nanoparticles as an efficient catalase mimic: Properties, mechanism and its electrocatalytic sensing application for hydrogen peroxide

• The catalase-like activity of Co3O4 nanoparticles could be tunable by the pH.
• Compared to catalase, Co3O4 nanoparticles had the efficient catalytic ability.
• Hydroxyl radicals took part in the catalytic recycles.
• Co3O4 nanoparticles were used as the amperometric sensor for the detection of H2O2.

Nanomaterial-based enzyme mimics have recently attracted considerable interest due to their easy preparation, low cost, high stability and so on. Herein Co3O4 nanoparticles (NPs) were used as a catalase mimic, catalyzing the decomposition of hydrogen peroxide to oxygen. The catalytic activity of Co3O4 NPs increased dramatically by adjusting the pH from acid to neutral and alkaline conditions. The catalytic activities and the mechanisms were investigated using the procedures of thermodynamics, steady-state kinetics and hydroxyl radical detection. The activation energy of Co3O4 NPs was determined to be 43.3 kJ mol−1 which was similar to 42.8 kJ mol−1 of catalase. The catalytic behaviour of Co3O4 NPs showed a typical Michaelis–Menten kinetics and good affinity to H2O2. The turnover number and specificity constant of Co3O4 NPs were very close to those of catalase. Based on the above results, Co3O4 NPs were an efficient catalase mimic. A catalytic mechanism was proposed where hydroxyl radicals took part in the catalytic recycles. Co3O4 NPs had better stability than natural catalase when they were exposed to solutions with different pH values and temperatures. As an efficient and stable catalase mimic, Co3O4 NPs were used as the amperometric sensor for the detection of hydrogen peroxide.

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