Three-dimensional nano-CuxO-MWCNTs-COOH/MXene heterostructure: An efficient electrochemical platform for highly sensitive and selective sensing of benomyl in fruit samples

Herein, a highly sensitive and selective electrochemical sensor for the detection of benomyl (BN), a typical benzimidazole fungicide was proposed based on hierarchical nano-Cu x O decorated MWCNTs-COOH/MXene (nano-Cu x O-MWCNTs-COOH /MXene) composite. The ternary heterostructure presents good electrical conductivity, large specific surface area, and high catalytic activity, exhibiting excellent electrocatalytic activity with enhanced electrochemical signals towards the oxidation of BN. Besides, the embedded nano-Cu x O particles possess strong affinity toward benzimidazole molecules, which could promote the preconcentration of BN, further enhancing the sensitivity, as well as ensuring the high selectivity. Benefitting from the synergistic effect of components in the composite, the developed sensor presents a broad linear range from 10.0 nM to 10.0 μM with a low limit of detection of 3.0 nM (S/N = 3). Meanwhile, the nano-Cu x O-MWCNTs-COOH/MXene electrode also displays good long-term stability and repeatability. Furthermore, this method was successfully applied for the detection of BN in apple samples, illustrating its promising practicability.