The peroxidase-like activity of Au NPs deposited inverse opal CeO2 nanozyme for rapid and sensitive H2O2 sensing

In this study, the hybrid nanozyme gold nanoparticles deposited CeO2 inverse opal photonic crystals (IOPCs) on the glass slide was fabricated by bestowing the hybrid with the beneficial porous morphology with its unique advantages: its surface valence states, high surface area, and copious active sites. The oxidase and peroxidase-mimicking activity was studied by observing the catalytic oxidation of chromogenic substrate 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) in the presence of H2O2, which can be visualized by the eyes. Au NPs and CeO2 IOPCs consisting of Ce3+ and Ce4+ can oxidize ABTS in the presence of H2O2 by mimicking peroxidase enzymes. The peroxidase-like activity of nanozyme was substantially improved by introducing light irradiation due to the photosensitive nature of the hybrid. The peroxidase-like activity of nanozyme enabled H2O2 linear detection over the range 9 to 500 μM, with a LOD of 2.7 µM. The acceptable nanozyme activity is probably owing to the easy access of H2O2 to the active sites of nanozyme. The porous architecture led to the easy channeling of reactants and products. The periodic architecture of the nanozyme also led to decent reproducibility. Without functionalization, the nanozyme can be a promising alternative to peroxidase enzymes for hydrogen peroxide measurements.