Electrochemical sensor based on graphene oxide/PEDOT:PSS composite modified glassy carbon electrode for environmental nitrite detection

Abstract

In this study, an electrochemical sensor was developed for nitrite (NO2−) sensing based on the modification of the surface of a glassy carbon electrode (GCE) with a graphene oxide (GO) and poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) composite. The structure, morphology, and electron transfer resistance of the GO/PEDOT:PSS composite were characterized using Raman and infrared spectroscopies, scanning electron microscopy, and electrochemical impedance spectroscopy. Based on the results, the GO/PEDOT:PSS-modified GCE displays a higher intensity peak current for NO2− oxidation (∼8 times higher) than bare GCE over a potential range of 0.4–1.1 V vs. Ag/AgCl. In addition, this proposed NO2− sensor shows a linear dynamic range in the concentration range of 1–200 μM, with a regression coefficient of 0.99. The limit of detection and limit of quantitation of NO2− measurement were determined as 0.5 μM (0.0345 μg mL−1) and 5 μM (0.345 μg mL−1), respectively. Moreover, the stability and reproducibility of the GO/PEDOT:PSS-modified GCE are excellent and its selectivity is good, with a relative standard deviation of< 5%. The performance of this proposed sensor was also compared with the standard spectrophotometric technique used in NO2− determination in real samples and showed no significant difference at a confidence interval of 95%. Therefore, it can be concluded that the as-prepared NO2− sensor based on the GO/PEDOT:PSS-modified GCE shows good analytical performance and is a potential candidate for practical application in environmental NO2− detection.