Preparation of Flower-like NiMnO3 as Oxidase Mimetics for Colorimetric Detection of Hydroquinone

Hierarchical flower-like NiMnO3 composites were facilely prepared by template-free hydrothermal treatment and calcined under mild conditions. Due to the strong ability to absorb oxygen, the as-prepared NiMnO3 composites were endowed with oxidase-like activity to catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to a blue product without H2O2. Investigations on the mechanism indicate that oxidase-like activity of NiMnO3 composites originates from superoxide radical generation. The oxidase-like activity of the NiMnO3 composites was selectively inhibited by hydroquinone (HQ), which could reduce oxTMB to colorless TMB and could result in significant blue color fading. With increasing HQ concentration, the absorbance at 652 nm decreased gradually. A colorimetric method based on the NiMnO3 composite was established for the detection of the concentration of HQ in water and practical samples. This assay was simple, rapid, sensitive, and selective for detecting HQ with a low detection limit of 0.68 μM and an excellent linear range of 1–85 μM. This colorimetric sensor could be effectively applied for the detection of HQ in real water samples with RSD < 3.89% (n = 3) and Er < 2.17% (n = 3). The above results illustrated that the NiMnO3 composites have outstanding potential for application in environmental chemistry.