Core-shell structure N-doped graphene quantum dots Fe3O4/Co3O4 nanoparticles for colorimetric detection of H2O2

Hydrogen peroxide (H 2 O 2 ) is an environmentally friendly intermediate in the environmental field and also plays an important role in human metabolism, but the production and accumulation of excessive H 2 O 2 will cause harm to the human body, resulting in serious damage to cells. Therefore, N-doped graphene quantum dots Fe 3 O 4 /Co 3 O 4 nanoparticles with core-shell structure were prepared by in-situ synthesis and precipitation. The experimental results show that the prepared Co 3 O 4 nanoparticles have more efficient peroxidase activity than Co 3 O 4 nanoparticles alone. It can catalyze the oxidation of 3, 3, 5, 5-tetramethylbenzidine (TMB) to produce a blue product (TMBox) in the presence of H 2 O 2 . In addition, Co 3 O 4 with negative charge in the shell can produce a strong electrostatic driving coordination effect with positively charged TMB, which enhances the affinity between the nanoparticles and the substrate, and selectively catalyzes H 2 O 2 oxidation of colorless TMB to turn it blue. Based on these experimental results, a simple, low-cost, and efficient colorimetric method for H 2 O 2 detection was established, which showed a sensitive response to H 2 O 2 in the range of 0.02–2.5 μM with a detection limit of 2.3 nM. In addition, due to the magnetic properties of the prepared nanoparticles, they could be easily recovered by applying a magnetic field. This research provides a viable approach for magnetic nanomaterials with encouraging prospects for environmental monitoring, biosensing, and more.