Three-dimensional polymer phenylethnylcopper/nitrogen doped graphene aerogel electrode coupled with FeO NPs nanozyme: Toward sensitive and robust photoelectrochemical detection of glyphosate in agricultural matrix.

Background: Presently, glyphosate (Gly) is the most extensively used herbicide globally, Nevertheless, its excessive usage has increased its accumulation in off-target locations, and aroused concerns for food and environmental safety. Commonly used detection methods, such as high-performance liquid chromatography and gas chromatography, have limitations due to expensive instruments, complex pre-processing steps, and inadequate sensitivity. Therefore, a facile, sensitive, and reliable Gly detection method should be developed.

Results: A photoelectrochemical (PEC) sensor consisting of a three-dimensional polymer phenylethnylcopper/nitrogen-doped graphene aerogel (PPhECu/3DNGA) electrode coupled with FeO NPs nanozyme was constructed for sensitive detection of Gly. The microscopic 3D network of electrodes offered fast transfer routes for photo-generated electrons and a large surface area for nanozyme loading, allowing high signal output and analytical sensitivity. Furthermore, the use of peroxidase-mimicking FeO NPs instead of natural enzyme improved the stability of the sensor against ambient temperature changes. Based on the inhibitory effect of Gly on the catalytic activity FeO NPs, the protocol achieved Gly detection in the range of 5 × 10 to 1 × 10 mol L. Additionally, feasibility of the detection was confirmed in real agricultural matrix including tea, maize seedlings, maize seeds and soil.

Significance: This work achieved facile, sensitive and reliable analysis towards Gly, and it was expected to inspire the design and utilization of 3D architectures in monitoring agricultural chemicals in food and environmental matrix.