An ultrasensitive electrochemical sensor based on a graphitic carbon nitride/cuprous oxide nanocomposite for monitoring Tetrabromobisphenol A in environmental waters

Tetrabromobisphenol A (TBBPA), a hazardous brominated flame retardant prevalent in aquatic environments, poses risks to ecological systems and public health, underscoring the need for advanced and reliable monitoring tools. In this study, an electrochemical sensor based on a graphite carbon nitride/cuprous oxide (g-C 3 N 4 /Cu 2 O) nanocomposite was developed for sensitive TBBPA detection. The g-C 3 N 4 /Cu 2 O composite, uniformly modified onto a glassy carbon electrode, improved the dispersion of Cu 2 O, facilitated interfacial electron transfer, and provided abundant electroactive sites, thereby markedly improving the electrocatalytic oxidation of TBBPA. Density functional theory calculations indicated strong adsorption interactions and interfacial charge transfer between TBBPA and the composite, helping explain the enhanced sensing performance. Under optimized conditions, the sensor exhibited a wide linear detection range from 0.01 nM to 1 μM with an ultralow detection limit of 3.98 pM. This performance demonstrated the superior sensitivity of the sensor compared with most previously reported electrochemical sensors for TBBPA and confirmed its suitability for trace-level environmental analysis. The sensor also exhibited remarkable selectivity toward TBBPA in the presence of common interfering species, including ubiquitous inorganic ions (Na + , K + , Fe 2+ ), as well as structurally related phenolic compounds such as bisphenol A, hydroquinone, and catechol. In addition, the sensor displayed outstanding repeatability, reproducibility, and long-term stability. Its practical applicability was successfully validated through accurate determination of TBBPA in real river water samples from the Yitong River, demonstrating its reliability and strong potential for on-site environmental monitoring.