Preparation of g-C₃N₄/Co₃O₄/NS-CQDs Composite Materials and Their Application in the Detection of Hydrogen Peroxide and Glucose

Abstract

g-C3N4, 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-C3N4 (7NSC-g), verifying its peroxidase-like activity. Based on this, a ternary composite of Co3O4 in different forms and 7NSC-g was developed to enhance peroxidase activity, to design a g-C3N4-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 H2O2. UV-Vis spectrophotometry measured absorbance changes to determine target concentrations. The results show Co3O4 doping improves catalytic activity, with larger specific surface area providing more activation sites. The highest activity of g-C3N4/NS-CQDs/Co3O4 was at 5% floral Co3O4, being efficient due to Co3O4’s electron-transfer acceleration and hydroxyl-radical mechanism. Under optimal conditions, the composite detected H2O2 (10.0–230.0 μM, detection limit of 0.031 μM) and glucose (10.0–650.0 μM, detection limit of 1.024 μM).

Keywords

• g-C₃N₄
• peroxidase mimic
• N,S-doped carbon quantum dots (NS-CQDs)
• Co₃O₄
• colorimetric detection