Ultrasound-assisted one-step reduction and self-assembly of carbon dots-reduced graphene oxide: Mechanism investigation and solid phase microextraction of ultra-trace organochlorine pesticides

In this work, carbon dots-reduction graphene oxide (CDs/RGO) composite was synthesized by a facile and green strategy with one-step reduction and self-assembly of GO and CDs under ultrasonic treatment. CDs was successfully applied to reduce GO to RGO, and anchored on the surface of RGO simultaneously under ultrasonic treatment within 20 min. The reduction mechanism was demonstrated by density functional theory calculations, which confirmed the electron transfer from CDs to GO and supplemented the reduction mechanism of GO by CDs. Characterizations results showed that the as-prepared CDs/RGO composite exhibited lamellar spacing and wrinkled structures, and abundant chemical groups in comparison to RGO reduced by sodium borohydride. In view of excellent morphology and chemical structures, the CDs/RGO composite was used for the first time in extraction and determination of ultra-trace organochlorine pesticides (OCPs) from water by means of solid phase microextraction (SPME) coupled with gas chromatography-mass spectrometry. The CDs/RGO coating presented superior extraction capacities for OCPs compared with commercial SPME coatings and sodium borohydride reduced RGO. The proposed analytical method exhibited high sensitivity with detection limit of 0.003–0.051 ng/L, excellent linearity in concentration range of 0.050–2500 ng/L, and satisfactory precision for seven OCPs. The excellent performances made the proposed method to be applied in determination of ultra-trace OCPs in real water successfully. This work proposed a green approach to synthesize CDs/RGO composite and a potential coating sorbent for SPME.