Mesoporous Cu2O–CuO/O–g-C3N4 nanocomposite with enhanced peroxidase-like activity for the colorimetric H2O2 sensing

Herein, Cu₂O–CuO incorporated oxygen-doped g-C₃N₄ has been utilized for the colorimetric sensing of H₂O₂ by the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB). The material characterization studies via XPS, XRD, FTIR spectroscopy etc. proved the presence of both Cu₂O and CuO as well as the doping of oxygen on g-C₃N₄. The use of citric acid in the preparation led to a mesoporous architecture together with oxygen doping to g-C₃N₄. The high peroxidase-like activity of the present Cu-incorporated exfoliated g-C₃N₄ nanoenzyme aroused from the improved features such as smaller band gap, porous nature, oxygen doping to g-C₃N₄, and thus resulted fast electron mobility and transfer. Michaelis–Menten mechanism is used to study the kinetics, where the obtained K_m and V_max values are found to be relevant in comparison with the reported studies. From the mechanistic investigation, the reactive oxygen species involved in the TMB oxidation is ascertained as oxygen superoxide radical anion (^•O₂⁻). The linear range in sensing is 2.5–250 µM with a limit of detection (LOD) of 1 µM H₂O₂. The nanoenzyme showed the least amount of interference and a promising reusability in H₂O₂ sensing.

Graphical abstract