Noble metal-free modified electrode of exfoliated graphitic carbon nitride/ZnO nanosheets for highly efficient hydrogen peroxide sensing

Graphitic carbon nitride (g-C₃N₄)/ZnO nanosheets were coated on the surface of fluorine-doped tin oxide (FTO) glass as a noble metal-free g-C₃N₄/ZnO/FTO electrode, which was used for the determination of hydrogen peroxide (H₂O₂). The exfoliated g-C₃N₄ nanosheets were firstly prepared and then ZnO nanosheets were grown on g-C₃N₄ nanosheets by a microwave-assisted hydrothermal synthesis. The g-C₃N₄ nanosheets combined with ZnO nanosheets can greatly improve the adsorption of hydrogen peroxide and increase the conductivity of materials as well. The g-C₃N₄/ZnO nanosheets were characterized by powder X-ray diffraction (XRD), scanning electron microscopic (SEM), transmission electron microscopic (TEM), and X-ray photoelectron spectroscopy (XPS) analysis. Meanwhile, electrochemical measurements of the g-C₃N₄/ZnO/FTO electrode were utilized to investigate the amperometric sensing of hydrogen peroxide. The prepared g-C₃N₄/ZnO/FTO electrode revealed the sensitivity of 540.8 μA mM⁻¹ cm⁻² at −0.5 V with the linear response range from 0.05 to 14.15 mM, which even was superior to some noble metal-decorated H₂O₂ sensors. Additionally, the g-C₃N₄/ZnO/FTO electrode also showed the reliable operational and environmental stability for electrochemical reduction of H₂O₂.