Fig. 3.

a UV–vis absorption spectra of the catalyzed oxidation of TMB (oxTMB) catalyzed by Fe₃O₄ NPs with 100 mM H₂O₂ under the reaction buffer (pH = 6). b Time-dependent absorbance changes at 652 nm as a result of the catalyzed oxidation of TMB at different H₂O₂ concentrations (10, 20, 50, 80, 100 × 10⁻³ M). c Michaelis–Menten kinetic analysis and d Lineweaver–Burk plotting for Fe₃O₄ with H₂O₂ as substrate. The steady-state catalytic rate (v) was calculated from the initial slopes of absorbance versus time plots in panel b. e Degradation rates of MB under different conditions ([Fe₃O₄@Pt]: 200 µg/mL for Fe₃O₄, AC output current: 10 mA, [MB]: 2.5 × 10⁻⁵ M). f Degradation rates of MB in the presence of Fe₃O₄@Pt NPs with different concentrations under electric field