Molecular chelating and shielding operation for organic photoelectrochemical transistor detection of chlorpyrifos

Chlorpyrifos (CPF), as one of the four major insecticides for pest control, is widely used in agricultural production, but its continuous accumulation has caused serious pollution to the environment. In this paper, we developed a novel organic photoelectrochemical transistor (OPECT) sensor for the CPF detection using a BiOI@Bi₂S₃ photogate. The molecular chelating of CPF with surface Bi(III) ions would induce the shielding effect that altered the OPECT response. With a high current gain at zero bias voltage, the as-developed OPECT device was able to detect CPF sensitively and specifically with a linear range of 1 × 10^-4-1 × 10² ng mL^-1 and a detection limit (S/N = 3) of 0.03 pg mL^-1. Meanwhile, the OPECT detection of CPF in water samples, lettuce and apple were also conducted, with the recoveries of 94.6%-103.1 % and the relative standard deviations (RSD) of 1.51%-4.26 % for the samples. This work reports a new OPECT strategy for CPF detection, which reveals the potential of OPECT for detecting other organophosphorus pesticides.