Highly efficient visible light driven photocatalytic inactivation of E. coli with Ag QDs decorated Z-scheme Bi2S3/SnIn4S8 composite

Here, a novel Ag QDs modified Bi2S3/SnIn4S8 composite with direct Z-scheme charge carriers transfer model was synthesized through combining with chemical reduction and solvothermal methods for high-efficient photo-disinfection toward E.coli under visible light stimulation (lambda > 420 nm). The 200 Ag QDs/Bi2S3/SnIn4S8 hybrid exhibited the strongest photocatalytic inactivation activity of E.coli which could completely inactivate the bacteria with 4 h visible light excitation. The photoinactivation mechanism can be ascribed to the wreck of cell membrane, leakage and damage of intracellular biomolecules including protein and DNA as demonstrated by fluorescence-based live/dead stain, sodium dodecyl sulfate polyacrylamide gel electropheresis (SDS-PAGE) and agarose gel electrophoresis (AGE). Moreover, the trapping and verification experiments of free radical revealed that the reactive species h(+), e(-) and O-center dot(2)- play the chief role in photodisinfection reaction. The photoelec-trochemical techniques disclosed that the enhanced photocatalytic activity could mainly be assigned to the synergistic effect of Ag QDs, Bi2S3 and SnIn4S8, which could improve the visible light absorption ability, separation and transfer efficiency of photoinduced charge carriers, enlarge specific surface area through the surface plasma resonance (SPR) effect and the electron trapped and injected of Ag QDs. Additionally, the Ag QDs/Bi2S3/SnIn4S8 composite displayed a potential application in organic contaminant removal. Our work firmly exhibited a promising environmental friendly substitutable strategy for wasterwater purification caused by pathogenic bacteria and organic pollutant.