Fabrication of CeVO4 as nanozyme for facile colorimetric discrimination of hydroquinone from resorcinol and catechol

A simple method was proposed for the preparation of CeVO 4 . The as-synthesized CeVO 4 was, for the first time, demonstrated to exhibit both peroxidase-like and oxidase-like activity, which catalyzes the oxidation of 3, 3′, 5, 5′-tetramethylbenzidine (TMB) to form a typical blue solution in the presence or absence of H 2 O 2 . Moreover, the mechanism of its dual-enzyme activity was investigated in detail. The Michaelis constant ( K m ) value for CeVO 4 (0.136   mM) was lower than that of horseradish peroxidase (0.424   mM) with TMB as the substrate. Interestingly, hydroquinone (H 2 Q), dihydroxybenzene isomer, undergoes reduction accompanying the oxidation of TMB by the CeVO 4 oxidase mimic along with a visible color change, while the other two dihydroxybenzene isomers, i.e., resorcinol (RC) and catechol (CC), do not. Based on these findings, a colorimetric platform was developed to discriminate H 2 Q from RC and CC. Under optimal conditions, a linear relationship between the H 2 Q concentration and absorbance was observed from 0.05 to 8   μM, and a limit of detection of 0.04   μM was achieved. Moreover, this colorimetric platform can selectively reveal H 2 Q concentrations in the presence of other dihydroxybenzene isomers.