Self-powered photoelectrochemical sensor based on molecularly imprinted polymer-coupled CBFO photocathode and Ag₂S/SnS₂ photoanode for ultrasensitive dimethoate sensing

Dimethoate (DIM) is one of the most extensively applied organophosphorus pesticides (OPs), which is used to boost farm productivity due to its high insecticidal efficacy. However, the excessive use of DIM can result in the extensive contamination of soil, groundwater and food. Monitoring of DIM in environmental and food samples is crucial in view of its potential health risks and environmental hazards from excessive residues. The expensive equipment and complex operations for current detection methods greatly limit their practical applications. Herein, a self-powered photoelectrochemical (PEC) sensing platform based on Ag₂S/SnS₂ photoanode, iron-doped cobalt borate (CBFO) photocathode, and molecularly imprinted polymers (MIPs) was proposed for the detection of DIM. The molecularly imprinted polymers at CBFO photocathode endow the self-powered PEC sensor with high selectivity. The Ag₂S/SnS₂ photoanode enhances the efficient of electron transfer between the photoanode and photocathode, contributing to the high sensitivity of PEC sensor. The self-powered molecularly imprinted PEC sensor exhibits outstanding sensitivity and selectivity for DIM at concentrations from 1 × 10⁻² to 1 × 10⁵ nM with a detection limit of 5.9 pM. Excellent recoveries (95.4 ± 2.6 %, 98.4 ± 2.3 %, 106.3 ± 3.3 %) were achieved in spiked crown pear samples, indicating that the molecularly imprinted PEC sensor is capable of detecting DIM in real samples. This research provides a novel simple, fast, highly selective and sensitive self-powered molecularly imprinted photoelectrochemical sensing platform for detection of DIM. The fabricated PEC sensor offers a promising candidate for the detection method of organophosphorus pesticides residues, which is of great significance for the fields of food safety and environmental protection.