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Corresponding Author

Bing-Qian Liu(liubingqian96@126.com)

Abstract

Nitrite, a widespread raw material, is harmful to human health for long-term consumption. At present, the detection methods of nitrite mainly include chemical analysis, fluorescence, ultraviolet spectrophotometry and chromatography. These methods have ideal sensitivity and selectivity, but also have some characteristics: cumbersome operation, expensive equipment and professional personnel. Therefore, the development of a simple and sensitive nitrite assay is of great significance. In this paper, the Au/rGO/FeOOH composite materials, which revealed good synergistic catalytic performance among the three elements in the composite, were prepared by simple hydrothermal method and reduction method for the first time with large specific surface area and good electrical conductivity. A one-step electrochemical sensor was constructed by using a traditional three-electrode system for detecting NO2-. Of course, the Au/rGO/FeOOH composite modified FTO was regarded as the working electrode. When the target NO2- existed, the current increased because the material on the electrode could electro-catalyze NO2- to NO3-. When the NO2- was oxidized, the electron was transferred from NO2- to the Au/rGO/FeOOH composite. And the rGO with a large specific surface area and good conductivity in the composite would rapidly transfer electrons to the FTO electrode, thus, enhancing the current signal. Quantitative analysis of NO2- could be obtained according to the current intensity which is positively correlated with the concentration of the target. Under the optimal experimental conditions, nitrite was quantitatively detected by differential pulse voltammetry with a linear range of 0.001 ~ 5 mmol·L-1 and a detection limit of 0.8 μmol·L-1 (S/N = 3), and the response time was less than 2s. Moreover, the sensor exhibited good selectivity and reproducibility, and could be applied to actual samples. The excellent sensitivity for rapid detection of NO2- may be derived from two aspects: 1. the unique structure of rGO FeOOH expands the surface area of the electrode, and further speeds up electron transfer during electrochemical reactions; 2. the composite material has synergistic electrocatalytic oxidation performance among Au, rGO and FeOOH. More importantly, the one-step determination of NO2- could be realized accompanying with the simple fabrication of electrode and quick response (~ 2s). It also provides a new idea for the application of metal-organic framework materials in electrochemical field.

Graphical Abstract

Keywords

nitrite, Au/rGO/FeOOH, electrochemical sensor, one-step detection

Publication Date

2022-08-28

Online Available Date

2022-01-10

Revised Date

2021-12-20

Received Date

2021-10-20

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