Facile preparation of Fe₃O₄/CNTs nanocomposites by catalytic chemical vapor deposition for nonenzymatic hydrogen peroxide sensor

Hydrogen peroxide is involved in multiple life processes and closely related to the development of various diseases. Therefore, the rapid, simple and low-cost detection of H₂O₂ in blood is significant. Here we developed a one-step method to prepare ferric oxide and carbon nanotube nanocomposites (Fe₃O₄/CNTs) for nonenzymatic electrochemical detection of H₂O₂. Fe₃O₄/CNTs were synthesized when growing CNTs by chemical vapor deposition (CVD) with salt supported Fe₂O₃ nanoparticles (Fe₂O₃/NaCl) as catalysts. The results showed that the Fe₃O₄/CNTs nanocomposites 0.5Fe-4H2O-3 obtained with 0.5 wt%-Fe₂O₃/NaCl catalyst, ethyl acetate: water: oxygen molar ratio of 1:4:2, growth duration of 3 hours exhibited the optimal detection performance. The linear detection range of the sensor was 10 ∼ 750 μM and 0.75 ∼ 19 mM with a limit of detection (LOD) of 1.9 μM (S/N = 3) at a detection potential of −0.6 V (vs. Ag/AgCl). Furthermore, this sensor demonstrated excellent anti-interference performance and stability, achieving good recovery rates when detecting H₂O₂ in pig serum. The 0.5Fe-4H2O-3 nanocomposites possess the highest Fe₃O₄ exposure and significantly lower electron transfer resistance compared to the mechanically mixed samples. Therefore, the one-step synthesis method can enhance the interaction between the oxide and the carbon nanotubes, thereby reducing impedance and improving the electrochemical detection performance.