Gold Nanoparticle/Chitosan@N,S Co-doped Multiwalled Carbon Nanotubes Sensor: Fabrication, Characterization, and Electrochemical Detection of Catechol and Nitrite

Given that catechol and nitrite can be easily released into the environment and cause serious damage to our physical and ecological environment, it is necessary to develop a fast and reliable detection method for catechol and nitrite analysis. In our work, an electrochemical catechol and nitrite sensor was created based on gold nanoparticles (AuNPs) deposited on chitosan@N,S co-doped multiwalled carbon nanotubes (CS@N,S co-doped MWCNTS) composite modified glassy carbon electrode. The preliminary prepared composite materials were characterized by transmission electron microscope, scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The AuNPs/CS@N,S co-doped MWCNTS modified electrode shows a good linear relationship between 1 μmol·L–1 (μM) and 5000 μM for catechol, and the detection limit was calculated as 0.2 μM. For nitrite the linear relationship was 1–7000 μM with the detection limit of 0.2 μM. The sensitivity of the created sensor was evaluated as 0.9081 μA·μM–1·cm–2 for catechol, and for nitrite it was 0.7595 μA·μM–1·cm–2. Also the sensor shows significant selectivity, reproducibility, and stability. Moreover, the modified electrode is also applied in tap water samples for the catechol measurement and nitrite in fermented bean curd, ham sausage, and mustard tuber samples.