Ferrocene-Grafted Carbon Nanotubes for Sensitive Non-Enzymatic Electrochemical Detection of Hydrogen Peroxide

Sensitive detection of hydrogen peroxide (H₂O₂) residue in aseptic packaging at point of use is critical to food safety. We present a sensitive non-enzymatic, amperometric H₂O₂ sensor based on ferrocene-functionalized multi-walled carbon nanotubes (MWCNT-FeC) and facile screen-printed carbon electrodes (SPCEs). The sensor utilizes the covalently grafted ferrocene as an effective redox mediator and the MWCNT networks to provide a large active surface area for efficient electrocatalytic reactions. The electrocatalytic MWCNT-FeC modified electrodes feature a high-efficiency electron transfer and a high electrocatalytic activity towards H₂O₂ reduction at a low potential of -0.15 V vs. Ag/AgCl. The decreased operating potential improves the selectivity by inherently eliminating the cross-reactivity with other electroactive interferents, such as dopamine, glucose, and ascorbic acid. The sensor exhibits a wide linear detection range from 1 μM to 1 mM with a detection limit of 0.49 μM (S/N=3). The covalently functionalized electrodes offered highly reproducible and reliable detection, providing a robust property for continuous, real-time H₂O₂ monitoring. Furthermore, the proposed sensor was successfully employed to determine H₂O₂ levels in spiked packaged milk and apple juice with satisfactory recoveries (94.33-97.62%). The MWCNT-FeC modified SPCEs offered a facile, cost-effective method for highly sensitive and selective point-of-use detection of H₂O₂.