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

Abstract The Au/Co 3 O 4 -CeO x nanocomposites (Au/Co 3 O 4 -CeO x NCs) have been synthesized successfully by a facile two-step method. It was proved that Au/Co 3 O 4 -CeO x 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 H 2 O 2 to generate a blue product. Furthermore, Au/Co 3 O 4 -CeO x NCs possessed a much higher affinity to H 2 O 2 and TMB than horseradish peroxidase (HRP). In view of the excellent peroxidase mimetic catalytic activity of Au/Co 3 O 4 -CeO x NCs, a novel, sensitive and efficient colorimetric sensor with Au/Co 3 O 4 -CeO x NCs as peroxidase mimics has been constructed unprecedentedly to detect H 2 O 2 . Under optimal conditions, the colorimetric platform showed a sensitive response to H 2 O 2 in the range of 10–1000 μM with a limit of detection of 5.29 μM. Moreover, fluorescent data proved that the Au/Co 3 O 4 -CeO x NCs could effectively catalyze the decomposition of H 2 O 2 into OH radicals. Thus, we believe that Au/Co 3 O 4 -CeO x NCs with high peroxidase-like activity can be employed as nanoenzyme for a wide range of promising applications in biotechnology and environment.