Facile preparation of urchin-like NiCo2O4 microspheres as oxidase mimetic for colormetric assay of hydroquinone

The hierarchical urchin-like NiCo2O4 microspheres were successfully fabricated by facile two-step method, including template-free hydrothermal and calcination. The prepared NiCo2O4 microspheres with amounts of absorbed oxygen were found to possess oxidase-like activity. They could catalytically oxidize 3,3',5,5'-tetramethylbenzidine (TMB) without the exogenous addition of H2O2, causing typical color reaction. But hydroquinone (HQ) could induce the reduction of oxTMB and result in a conspicuous blue color fading. In this paper, a simple and rapid colorimetric method for detecting trace amount of HQwas explored in-depth. Excellent linear relationship (5-110 mu M) and a low detection limit of 2.7 mu M were achieved. Meaningfully, this method could be well applied in real environmental samples with outstanding recoveries ranging from 97.07% to 103.52%. These primary results demonstrated that the NiCo2O4 microspheres have a great potential for applications in environmental chemistry. (C) 2017 Elsevier B.V. All rights reserved.