MoS2/MWCNT-COOH-Modified Glassy Carbon Electrode for Nitrite Detection in Water Environment

Abstract

Nitrite is harmful to people and animals when it is excessive in an environment. Traditional detection methods are time-consuming and are generally restricted by sensitivity. In this study, a simple and efficient electrochemical sensor made of a glassy carbon electrode (GCE), modified with MoS2 nanosheets/carboxylic multiwall carbon nanotubes (MoS2/MWCNT-COOH), was used to detect nitrite. Cyclic voltammetry (CV) was used for drawing the standard curve of nitrite. The properties of the modified materials were analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical impedance spectroscopy (EIS). The modified electrode presents a great response to nitrite, shows a wide sensing range (10–10,000 μM) and shows a low detection limit (3.6 μM). The characterization of nanomaterials indicates that MoS2/MWCNT-COOH has a big surface area (150.3 m2 g−1) and abundant pores (pore volume is 0.7085 cm3 g−1). In addition, the sensor shows high sensitivity (0.35 μA μM−1 cm−2), good reproducibility (RSD is 2.2%), and good stability (the responding current only decreased about 4% after 2 weeks). Therefore, the MoS2/MWCNT-COOH-modified electrode is a potential analytical method in nitrite determination.