Colorimetric and ultrasensitive detection of H2O2 based on Au/Co3O4-CeOx nanocomposites with enhanced peroxidase-like performance

The Au/Co3O4-CeOx nanocomposites (Au/Co3O4-CeOx NCs) have been synthesized successfully by a facile two-step method. It was proved that Au/Co3O4-CeOx NCs exhibited an excellent peroxidase-like activity and could efficiently catalyze the oxidition reaction of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2 to generate a blue product. Furthermore, Au/Co3O4-CeOx NCs possessed a much higher affinity to H2O2 and TMB than horseradish peroxidase (HRP). In view of the excellent peroxidase mimetic catalytic activity of Au/Co3O4CeOx NCs, a novel, sensitive and efficient colorimetric sensor with Au/Co3O4-CeOx NCs as peroxidase mimics has been constructed unprecedentedly to detect H2O2. Under optimal conditions, the colorimetric platform showed a sensitive response to H2O2 in the range of 10-1000 mu M with a limit of detection of 5.29 mu M. Moreover, fluorescent data proved that the Au/Co3O4-CeOx NCs could effectively catalyze the decomposition of H2O2 into center dot OH radicals. Thus, we believe that Au/Co3O4-CeOx NCs with high peroxidase-like activity can be employed as nanoenzyme for a wide range of promising applications in biotechnology and environment.