Peroxidase-like activity of bimetal Cu-Zn oxide mesoporous nanospheres for the determination of o-aminophenol.

To enhance the peroxidase-like performance and its application in detection of toxic o-aminophenol (o-AP), a kind of bimetal Cu-Zn oxide-based mesoporous nanosphere (Cu 2/3 Zn 1/3 O PNPs) was constructed under microwave-radiation conditions. Its mesoporous microstructure and peroxidase-like catalytic activity were investigated in detail. The results showed that Cu 2/3 Zn 1/3 O PNPs possessed a high specific surface area of 34.89 m 2 g -1 and a well-distributed mesoporous size of approximate 6.07 nm, which endowed the superior peroxidase-like performance. The material catalyzes the oxidization of 3,3',5,5'-tetramethylbenzidine (TMB) with K m /V max of 0.104 mM/3.79 × 10 -8  M·s -1 in the presence of H 2 O 2 . Especially o-AP could exclusively deteriorate the characteristic UV-Vis absorbance intensity at 653 nm (A 653 ) of the Cu 2/3 Zn 1/3 O PNPs-TMB-H 2 O 2 system with obvious color change from blue to colorless. Under the optimal conditions, the effect of some interfering substances was low and the limit of detection (LOD) for o-AP was 1.65 × 10 -8  mol/L (S/N = 3). When applied to the colorimetric detection of o-AP in practice, the recovery was between 96.1 and 107.2% with R.S.D. less than 2.04%. The mechanism of synergic-enhancement peroxidase-mimic activity of Cu 2/3 Zn 1/3 O PNPs and its exclusive colorimetric response to o-AP were proposed as well.