Oxygen vacancy enhanced Co3O4/ZnO nanocomposite with small sized and loose structure for sensitive electroanalysis of Hg(II) in subsidence area water

Abstract

Metal-oxide based nanocomposites have superior benefits to fabricate sensing interface for electroanalysis of heavy metal ions (HMIs) due to the introduction of various advantages (i.e. environmentally friendly, low-cost and high activity) into one material. Herein, Co3O4/ZnO nanocomposite with small size (sub-40 nm) and abundant oxygen vacancy was successfully prepared through one-step hydrothermal synthesis and subsequent annealing treatment, as well as the engineering of Co-Zn molar ratio. Moreover, the loose structure of Co3O4/ZnO nanocomposite can effectively improve the exposure of active sites on surface and enhance mass transfer. As a result, the as-obtained Co3O4/ZnO sensor has an impressive performance with sensitivity of 504.74 μA μM-1 cm-2 for electroanalysis of Hg(II) by square wave anodic stripping voltammetry (SWASV). Otherwise, diverse detection performances of the product with different Co:Zn molar ratio are investigated, proving the superiority for constructing Co3O4/ZnO sensor with molar ratio of 2Co/Zn. In addition, the electroanalytical behavior of the proposed sensors toward Hg(II) in subsidence area water was also realized with considerable result. By designing multifunctional nanocomposite with bimetal oxide nanomaterials, this work will provide a novel strategy to gain nanocomposite with controlling morphology and enriching oxygen vacancies, which are expected to be excellent candidate electrode materials for electroanalysis.