Abstract: A stable CDs/CC superhydrophilic substrate material with uniform anchoring sites was constructed by growing carbon dots (CDs) containing oxygen functional groups on dielectric barrier discharge (DBD)-modified flexible carbon cloth (CC) using a hydrothermal method. The FeSe/CDs/CC nitrite electrochemical sensor was further constructed by growing flaky FeSe nanomaterials on this substrate by a simple and rapid microwave method, and was characterised by XRD, SEM, XPS and EDS. The electrochemical performance results showed that the successful modification of CDs and FeSe significantly improved the conductivity of CC. Under the optimal detection conditions, the oxidation peak current showed a good linear relationship with the nitrite concentration in the ranges of 0.3-10 μmol/L and 10-1000 μmol/L, with the sensitivities of 5477.80 μA﹒mmol/L﹒cm2 and 1828.84 μA﹒mmol/L﹒cm2, and the detection limit of 0.11 μmol/L, respectively.In addition, the sensor possessed excellent immunity to interferences, long-term stability, repeatability and reproducibility, and the recoveries of nitrite spiked in the fracture flowback fluid were in the range of 97.75%-103.12%.

Key words: FeSe/CDs/CC, Nitrite; Electrochemical sensor, Fracture flowback fluid