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 (center dot O-2(-)). The linear range in sensing is 2.5-250 mu M with a limit of detection (LOD) of 1 mu M H2O2. The nanoenzyme showed the least amount of interference and a promising reusability in H2O2 sensing.