Visual and rapid fluorescence sensing for hexavalent chromium by hydroxypropyl chitosan passivated bismuth-based perovskite quantum dots.

Abstract

Hydroxypropyl chitosan-Cs3Bi2Cl9 perovskite quantum dots (HPCS-PQDs) weresynthesized by a simple ligand-assisted reprecipitation method via green hydroxypropyl chitosan as the ligand and used as the specific signal of a fluorescence probe to achieve the highly sensitive detection of hexavalent chromium(Cr(VI)) and compared with chitosan-Cs3Bi2Cl9 QDs (CS-PQDs). HPCS-PQDs with multiple active hydroxyl passivations were found to enhance the photoluminescence quantum yield (PLQY) by 90%. After being placed in aqueous solution and irradiated with ultraviolet light for 96h the fluorescence intensity of HPCS-PQDs remained above 60%. The blue emission ofHPCS-PQDs hasa good selectivity and short response time (30s) for Cr(VI). Agood linear relationship is established between the fluorescence quenching rate of the HPCS-PQDs and concentration of Cr(VI) from 0.8 to 400µM, with a limit of detection (LOD) of 0.27µM. Thefluorescence quenching mechanism is the static quenching and internal filtration effect caused by HPCS-PQDs forming a non-fluorescent ground-state complex with Cr(VI). Thesensor cannot only be used to detectCr(VI) in water samples with high accuracy but canalso be prepared as a test paper for the detection for Cr(VI).