Novel Z-scheme AgI@PbBiO2Br heterojunction for efficient photodegradation of organic pollutants and bacteria inactivation: DFT simulation, explore active radicals, and mechanism insight

In this study, novel Z-scheme AgI@PbBiO₂Br heterojunctions were prepared using a simple in situ precipitation approach to effectively degrade organic pollutants and inactivate gram-negative Escherichia coli (E. coli) and gram-positive Staphylococcus aureus (S. aureus) bacteria when exposed to visible light. The prepared materials were comprehensively evaluated using several analytical procedures. The 20 %-AgI@PbBiO₂Br presented the best photocatalytic performance of all the catalysts prepared. The rhodamine B (RhB) molecules were significantly reduced within 70 min (98.72 %), showing a much higher degradation efficiency than bare AgI (73.58 %) and PbBiO₂Br (46.77 %) under the same conditions. The degradation of methyl orange (MO), neutral red (NR), and tetracycline (TC) by 20 %-AgI@PbBiO₂Br was also examined, resulting in nearly total elimination of MO, NR, and TC pollutants, respectively. In addition, the antibacterial efficacy of 20 %-AgI@PbBiO₂Br against E. coli and S. aureus reaches about 99.99 %. The improved photodegradation efficacy of AgI@PbBiO₂Br is owing to the construction of a heterojunction between AgI and PbBiO₂Br, which increases effective charge separation and visible light absorption, thus enabling the decomposition of pollutants. Cycling experiments confirmed the stability and reusability of the material, demonstrating exceptional photocatalytic durability. The photocatalytic mechanism was thoroughly examined by reactive species capture assays and ESR analysis, confirming that holes and superoxide radicals are crucial in the photodegradation system. Additionally, the density functional theory (DFT) simulations and liquid chromatography-mass spectrometry (LC-MS) helped to clarify the susceptible active sites and possible degradation pathways of RhB. Overall, this work underlines the considerable ability of AgI@PbBiO₂Br heterojunctions to effectively remove persistent pollutants from wastewater.