Signal-on photoelectrochemical sensing by highly stable perovskite nanocrystals based on in situ formation of heterojunction

Lead halide perovskites have garnered significant attention in the field of photoelectrochemistry due to their outstanding optical properties. Nevertheless, the pronounced susceptibility of perovskite to water poses a major limitation to its practical applications. A signal-on photoelectrochemical (PEC) sensor was constructed in this work using water-resistant perovskite nanocrystals for the detection of hydrogen sulfide. Specially, the electrode surface was modified with composite nanomaterials (CsPbBr3 @PEG-PCL). In the presence of H2S, efficient heterojunctions were formed through the in-situ generation of PbS on CsPbBr3 @PEG-PCL, thereby enhancing the photocurrent signal. The potential mechanism behind this signal enhancement was extensively discussed. The designed sensor exhibited a linear relationship with the concentration of H2S ranging from 0.02 to 120 mu M, with a detection limit of 6.67 nM. This work opens up new possibilities for utilizing halide perovskites in the field of sensing, with promising applications in areas such as food safety, environmental monitoring, and biomedical analysis.