Oxygen-doped ZnIn2S4 as a highly active and etchable photoactive material for chlorpyrifos detection.

[Display omitted] • Oxygen-doped ZnIn 2 S 4 (O-ZnIn 2 S 4) show much higher photoelectrochemical (PEC) activity than pristine ZnIn 2 S 4. • Oxygen doping in ZnIn 2 S 4 can decrease the band gap and increase the visible-light absorption. • Enzymatic reactions catalyzed by acetylcholinesterase and choline oxidase can produce H 2 O 2 to etch O-ZnIn 2 S 4. • Organophosphorus pesticides (OPs) inhibit the activity of acetylcholinesterase, enabling "signal-on" PEC detection of OPs. • The detection limit for chlorpyrifos detection is as low as 2 × 10−4 mg L−1. The development of a high-performance photoactive material and an effective and efficient analysis strategy are important for photoelectrochemical (PEC) analysis. We report here the enhanced PEC activity and etchable property of oxygen-doped ZnIn 2 S 4 (O-ZnIn 2 S 4) and its application for PEC detection of organophosphorus pesticides (OPs). O-ZnIn 2 S 4 prepared by thermally treating ZnIn 2 S 4 in air atmosphere can show much higher PEC activity than pristine ZnIn 2 S 4 , because oxygen doping can decrease the band gap and thereby increase the visible-light absorption. It is found that O-ZnIn 2 S 4 can be etched by hydrogen peroxide, so O-ZnIn 2 S 4 can be used for PEC analysis based on the etching strategy. Enzymatic reactions catalyzed by acetylcholinesterase and choline oxidase can produce hydrogen peroxide to etch the O-ZnIn 2 S 4 modified on photoelectrode, so a "signal-off" state is achieved. OPs can inhibit the activity of acetylcholinesterase, and the etching of O-ZnIn 2 S 4 is weakened, enabling "signal-on" PEC detection of OPs. Chlorpyrifos is selected as a model for PEC detection of OPs. The detection limit for chlorpyrifos detection is 2 × 10−4 mg L−1 with a linear range from 0.001 to 50 mg L−1. The present study not only develops a high-performance photoactive material for PEC analysis but also provides an efficient PEC sensing strategy based on ZnIn 2 S 4 etching. [ABSTRACT FROM AUTHOR]