Catalytic and electrocatalytic activities of Fe3O4/CeO2/C-dot nanocomposite

Fe3O4/CeO2/C-dot nanozyme as a hybrid nanocomposite was prepared and characterized. Fe3O4/CeO2/C-dot nanocomposite presents horseradish peroxidase-like catalytic activity due to the presence of triple nanozymes in the nanocomposite. The kinetic parameters of nanozymatic assay present Michaelis–Menten behavior. A colorimetric assay for determination of H2O2 was introduced based on the catalytic activity of Fe3O4/CeO2/C-dot nanocomposite in H2O2/TMB system. In the presence of nanozyme, H2O2 reduction occurs and TMB was oxidized to ox-TMB which causes a blue color in the system. In this manner, intensity of the blue color is dependent on H2O2 concentration. Also, Fe3O4/CeO2/C-dot nanocomposite exhibits electrocatalytic activity toward H2O2 reduction. Multi-walled carbon nanotube/ionic liquid paste (MWIL) electrode was modified by Fe3O4/CeO2/C-dot nanocomposite which reveals higher electrocatalytic activity toward hydrogen peroxide rather than Fe3O4/CeO2 and Fe3O4/C-dot-modified electrodes. Catalytic and electrocatalytic determination of hydrogen peroxide shows the linear ranges of 1.0 × 10–6–5.0 × 10–13 M and 2.0 × 10–8 to 1.0 × 10–6 M, respectively.