Preparation of g-CN/CoO/NS-CQDs Composite Materials and Their Application in the Detection of Hydrogen Peroxide and Glucose.

g-CN, a biocompatible material, has prominent applications in biology and is ideal for nano-enzyme studies. Though reported as a peroxidase mimic, its activity remains low. This group combined N,S-doped carbon quantum dots (NS-CQDs) with g-CN (7NSC-g), verifying its peroxidase-like activity. Based on this, a ternary composite of CoO in different forms and 7NSC-g was developed to enhance peroxidase activity, to design a g-CN-based composite enzyme. Characterizations determined the composition and morphology. Colorimetry evaluated peroxidase activity, where the simulated enzyme catalyzes blue product formation from the TMB substrate in the presence of HO. UV-Vis spectrophotometry measured absorbance changes to determine target concentrations. The results show CoO doping improves catalytic activity, with larger specific surface area providing more activation sites. The highest activity of g-CN/NS-CQDs/CoO was at 5% floral CoO, being efficient due to CoO's electron-transfer acceleration and hydroxyl-radical mechanism. Under optimal conditions, the composite detected HO (10.0-230.0 μM, detection limit of 0.031 μM) and glucose (10.0-650.0 μM, detection limit of 1.024 μM).