Advanced photoelectrochemical detection of paraquat based on plasmonic metal modified photocathode material

Paraquat (PQ) as a widely used herbicide has high toxicity. Therefore, it calls for development of sensitive analytic methods to monitor the residue of PQ in environment. In this work, a photoelectrochemical (PEC) sensing strategy via preparation of the photocathode of ITO/Au/Cu2O is proposed. The introduction of Au film in the PEC system significantly improves the photoelectric property of Cu2O, which may be attributed to the enhanced light utilization and the inhibited self-photoreduction of Cu2O. As expected, under the visible light illumination, the fabricated ITO/Au/Cu2O photocathode shows excellent sensitivity in determination of trace paraquat. The quantitative linear range is from 10-9 to 10-5 mol L-1 and the limit of detection (2.93 × 10-10 mol L-1) could be reached. For detection of real samples, the ITO/Au/Cu2O photocathode-based PEC sensor demonstrates interference-free, detection reproducibility and acceptable recoveries. This study highlights the heterostructure advantage of metal–semiconductor for promoting the PEC sensing application.