CeO2/Co3O4@N-doped hollow carbon microspheres with improved peroxidase-like activity for the determination of quercetin.

Abstract

Nanozymes, as substitutes for natural enzymes, have been used to construct some fast cheap sensing platforms by virtue of the high catalytic activity. Herein, we firstly study the peroxidase-like activity of CeO2/Co3O4@N-doped hollow carbon microspheres as nanozymes. In the presence of H2O2, CeO2/Co3O4@NCH exhibits high peroxidase-like activity evaluated by the catalytic oxidation of the chromogenic substrate, 3,3',5,5'-tetramethylbenzidine (TMB) into a blue oxTMB visually in 1min. The larger surface area, pore-like structure, and oxygen vacancies contribute to the enhanced peroxidase-like activity of CeO2/Co3O4@NCH. The active species •O2- is detected during the catalytic process. Thus, based on the excellent peroxidase-like activity of CeO2/Co3O4@NCH, a facile and effective biosensor is fabricated for sensitive and selective determination of H2O2 and quercetin, respectively. CeO2/Co3O4@NCH shows high affinity towards H2O2 (Km = 4.001mM) and TMB (Km = 0.086mM). The detection limit of H2O2 and quercetin is as low as 0.086mM and 1.19μM (3σ/slope), respectively. This work remarkably extends the utilization of CeO2/Co3O4@NCH in designing a colorimetric sensing platform related to biosensing, food, and environmental monitoring. A fast colorimetric sensing platform for quercetin based on the excellent peroxidase-like activity of CeO2/Co3O4@NCH.