A highly sensitive and visible-light-driven photoelectrochemical sensor for chlorpyrifos detection using hollow Co9S8@CdS heterostructures

A highly sensitive and visible-light-driven photoelectrochemical (PEC) sensor has been constructed for the quantitative assay of organophosphorus pesticides like chlorpyrifos (Chlo) using hollow Co9S8@CdS heterostructures. The Co9S8@CdS heterostructures were created by growing CdS onto Co9S8 surface via one-step oil-bath route, of which Co9S8 was fabricated with hollow tubular structures through the Co(CO3)0.35Cl0.2(OH)1.1-templated solvothermal method. It was discovered that the so-obtained Co9S8@CdS with direct Z-scheme heterojunctions could exhibit larger photocurrents than the Co9S8 or CdS because of the greatly enhanced separation efficiency of photo-generated carriers. What’s more, the photocurrent signal of Co9S8@CdS-based PEC sensor could be selectively inhibited with the addition of Chlo through the specific chelation between the N and S atoms of Chlo with CN and PS groups and Co sites of Co9S8@CdS so as to suppress the carriers transferring. The developed PEC sensor could exhibit a linear response for Chlo ranging from 0.050 to 1000 ppb, with the detection limit value down to 0.015 ppb, which was far below than those of currently reported PEC sensors. Besides, the proposed routes may provide guidelines for designing various direct Z-scheme heterojunction-based PEC analysis platforms for determining environmental pollutants like Chlo.