Highly efficient visible-light photoactivity of Z-scheme MoS_2/Ag_2CO_3 photocatalysts for organic pollutants degradation and bacterial inactivation

摘要

Here, a novel 2-scheme MoS2/Ag2CO3 heterojunction photocatalyst was assembled from two-dimensional MoS2 nanosheets and Ag2CO3 nanoparticles through facile hydrothermal and in-situ precipitation method. The MoS2/Ag2CO3 heterojunction exhibited much enhanced visible-light photocatalytic performance in probe experiment for organic pollutants degradation and Escherichia coli (E. coli) inactivation compared to pristine Ag2CO3 and MoS2. The degradation rates of Lanasol Red 5B, rhodamine B, ciprofloxacin, and metronidazole reached 95%, 90%, 80%, and 72%, respectively. On the other hand, E. coli was completely inactivated in 80 min in the presence of 5%-MoS2/Ag2CO3. The improved photocatalytic performance was ascribed to the enhanced photogenerated charge separation efficiency and increased lifetime of the charge carriers, proved by photoluminescence spectra, time-resolved fluorescence emission decay spectra, and electrochemical measures. In addition, the active species trapping and ESR experiments all indicated that holes (h(+)) exhibited a significant contribution and superoxide radicals (center dot O-2(-)) acted as assistants. Based on experiment results, the photocatalytic enhancement mechanism for organic pollutants degradation and E. coli inactivation was discussed. The effect of representative environmental factors on the degradation of Lanasol Red 5B was investigated. The experiment results indicated that the degradation efficiency was partially influenced in the presence of inorganic salt. Furthermore, the appearance of a small amount of Ag nanoparticles not only enhanced the charge transfer, but also improved the stability of photocatalyst. Overall, MoS2/Ag2CO3 heterojunction has a great application potential for future water purification.