Preparation of the layered structure Ag@Co3O4 composites as peroxidase memetic for colorimetric detection of ascorbic acid

Co3O4 nanosheets were synthesized by precipitation method. Ag nanoparticles was successfully reduced from AgNO3 solution and loaded onto Co3O4 nanosheets to synthesize [email protected]3O4 nanosheets. [email protected]3O4 layered composites had obvious peroxidase-like characteristics. In the presence of hydrogen peroxide, [email protected]3O4 layered composites could oxidize 3,3′,5,5′-tetramethylbenzidine (TMB, colorless) to oxidize TMB (ox-TMB, blue). Ascorbic acid (AA) selectively inhibited the peroxidase-like activity of [email protected]3O4 layered composites, reducing ox-TMB (blue) to TMB (colorless). With the increase of AA concentration, a large amount of ox-TMB was reduced to TMB and the solution faded from blue gradually. Correspondingly, the increase of AA concentration directly led to the gradual decrease of the absorbance of the reaction solution at 652 nm. The [email protected]3O4 colorimetric detection platform with a detection limit of 0.59 μM and a linear range of 2–60 μM was rapid, sensitive and selective.