Electrochemical activation of oxygen vacancy-rich TiO2@MXene as high-performance electrochemical sensing platform for detecting imidacloprid in fruits and vegetables.

Heterostructured TiO2@MXene rich in oxygen vacancies defects (VO-TiO2@MXene) has been developed to construct an electrochemical sensing platform for imidacloprid (IMI) determination. For the material design, TiO2 nanoparticles were firstly in situ grown on MXene and used as a scaffolding to prevent the stack of MXene nanosheets. The obtained TiO2@MXene heterostructure displays excellent layered structure and large specific surface area. After that, electrochemical activation is utilized to treat TiO2@MXene, which greatly increases the concentration of surface oxygen vacancies (VOs), thereby remarkably enhancing the conductivity and adsorption capacity of the composite. Accordingly, the prepared VO-TiO2@MXene displays excellent electrocatalytic activity toward the reduction of IMI. Under optimum conditions, cyclic voltammetry and linear sweep voltammetry techniques were utilized to investigate the electrochemical behavior of IMI at the VO-TiO2@MXene/GCE. The proposed sensor based on VO-TiO2@MXene presents an obvious reduction peak at -1.05 V(vs. Hg|Hg2Cl2) with two linear ranges from 0.07 - 10.0 µM and 10.0 - 70.0 µM with a detection limit of 23.3 nM (S/N= 3). Furthermore, the sensor provides a reliable result for detecting IMI in fruit and vegetable samples with a recovery of 97.9-103% and RSD≤ 4.3%. A sensitive electrochemical sensing platform was reported for imidacloprid (IMI) determination based on heterostructured TiO2@MXene rich in oxygen vacancy defects.