Potential of novel dual Z-scheme carbon quantum dots decorated MnIn 2 S 4 /CdS/Bi 2 S 3 heterojunction for environmental applications.

In this work, CQDs decorated MnIn 2 S 4 /CdS/Bi 2 S 3 heterojunction was prepared successfully by hydrothermal technique for photocatalytic disinfection of Escherichia coli (E. coli) and mineralization of methyl orange (MO) dye. The charge transferal route and mineralization process in CQDs-MnIn 2 S 4 /CdS/Bi 2 S 3 heterojunction were comprehensively investigated by advanced spectroscopic techniques. The improved visible-light activity and enhanced photo-generated charge transferal efficacy caused dual Z-scheme CQDs-MnIn 2 S 4 /CdS/Bi 2 S 3 heterojunction to achieve boosted photodegradation ability. The catalytic degradation trend was followed as CQDs-MnIn 2 S 4 /CdS/Bi 2 S 3  > MnIn 2 S 4  > CdS > Bi 2 S 3 . The dye was mineralized within 180 min under visible light irradiation. The effect of reaction parameters, pH effect, catalyst dosage, and H 2 O 2 addition on MO degradation was also investigated. The degradation rate was maximal at pH 4 with a pseudo-first-order rate constant, 0.0438 min -1 . The assessment of antibacterial properties revealed that CQDs-MnIn 2 S 4 /CdS/Bi 2 S 3 composite effectively inactivated E. coli under visible light. Scavenging experiments, transient photocurrent response, and electron spin resonance spectroscopy suggested that • [Formula: see text] and holes were the dominant reactive species. The Z-scheme heterojunction is recyclable up to ten photocatalytic cycles according to recycling experiments. This research indicates the importance of dual Z-scheme CQDs decorated MnIn 2 S 4 /CdS/Bi 2 S 3 heterojunction in wastewater remediation.