Target-assisted self-powered photoelectrochemical sensor based on Ag2S/BiOCl heterojunction for ultrasensitive chlorpyrifos detection

Chlorpyrifos (CPF), a widely used organophosphorus pesticide, presents substantial risks to both environmental and human health due to its persistent accumulation, thereby necessitating the development of effective detection methods. Self-powered photoelectrochemical (PEC) sensors, as an innovative technology, address the limitations inherent in conventional sensors, such as susceptibility to interference and inadequate signal response. Herein, we synthesized Ag₂S/BiOCl as a photosensitive material, employing it as a light-harvesting substrate and a signal-transducing platform to develop a self-powered PEC sensor for the detection of CPF. Ag₂S/BiOCl composite exhibited a markedly enhanced photocurrent response in comparison to either Ag₂S or BiOCl individually. CPF possesses distinctive chemical bonds, and upon incubation on the electrode surface, it forms chelates with Bi (III) within the Ag₂S/BiOCl heterojunction. This interaction effectively impedes the transfer of photogenerated charges, resulting in a pronounced decrease in the original PEC signal, thereby facilitating the rapid and sensitive detection of CPF. This self-powder PEC sensor exhibited excellent linearity over the concentration range of 10.0 pg mL^-1-100.0 ng mL^-1, with a detection limit of 1.5 pg mL^-1. The successful application of this work in real samples highlights its strong potential for monitoring of CPF residues, while also demonstrating its broader applicability for detecting other contaminants.