Three-Dimensional Carbon Nanotube-Doped Hydrogel Network Enabling Sensitive Electrochemical Detection of Hydrogen Peroxide

Abstract

In this work, a hydrogen peroxide (H2O2) electrochemical sensor was constructed by co-doping carbon nanotubes (CNTs) into a cross-linked hydrogel (HG) network. The hydrogel forms a robust three-dimensional porous structure on the electrode and adheres strongly to the glassy carbon surface. Incorporating CNTs not only supplies additional electrocatalytic sites but also enhances electron transfer, thereby accelerating the H2O2 reduction reaction. Successful integration of CNTs into the hydrogel framework was confirmed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). Electrochemical measurements showed that the optimized H2O2 sensor exhibited a linear response from 0.05 to 60 mM, with a detection limit of 4.8 μM. The electroactive surface area of the glassy carbon electrode increased from 0.071 cm 2 for the bare electrode to 0.082 cm 2 after modification with HG/-OH containing CNTs (CNTs-OH). The sensor also displayed excellent reproducibility (RSD = 1.4%, n = 5), stability (current change of only 2.4 μA after 100 continuous scans), and anti-interference performance (maximum interference signal was 3.5% of the initial response). The conductive hydrogel developed here provides a promising platform material for the future design of flexible and portable H2O2 sensors.