Rapid colorimetric sensing of ascorbic acid based on the excellent peroxidase-like activity of Pt deposited on ZnCo2O4spheres

Pt deposited ZnCo(2)O(4)nanocomposites (Pt/ZnCo2O4) were prepared by a two-step method and found to possess excellent intrinsic peroxidase-like activity. With the aid of a colorless peroxidase substrate, 3,3 ',5,5 '-tetramethylbenzidine (TMB), the peroxidase-like activity of Pt/ZnCo(2)O(4)was evaluated in the presence of H2O2, which conforms to the Michaelis-Menten kinetic equation. The colorless TMB rapidly turned into a blue product (oxTMB) in just 3 min. Pt/ZnCo(2)O(4)has a higher affinity for H(2)O(2)and TMB compared to natural horseradish peroxidase (HRP) and can be used as a peroxidase mimic for establishing a colorimetric sensing platform. Importantly, fluorescent probe and electrochemical data verify that the catalytic activity of Pt/ZnCo(2)O(4)is due to the accelerated electron transfer between H(2)O(2)and TMB. Furthermore, the peroxidase-like activity of Pt/ZnCo(2)O(4)was significantly inhibited by ascorbic acid (AA), resulting in the fading of blue oxTMB. Based on this, a simple and efficient colorimetric sensor for H(2)O(2)and AA has been constructed. Under optimal conditions, the linear response ranges of H(2)O(2)and AA are 100-2000 mu M and 1-15 mu M, respectively. The detection limits of H(2)O(2)and AA are 26.44 mu M and 0.456 mu M, respectively.