Enhancement of photocatalytic disinfection performance of the Bi4O5Br2 with the modification of silver quantum dots

Here, a novel Ag quantum dots (Ag QDs) with diameter 3.1–10 nm modified Bi4O5Br2 composite system was firstly fabricated via the facile mechanical agitation method and the photocatalytic ability of Ag QDs/Bi4O5Br2 was evaluated by disinfection towards Escherichia coli (E.coli) under visible light stimulation (λ > 420 nm). The Ag QDs/Bi4O5Br2 composites displayed the superior photocatalytic disinfection ability to the pure Bi4O5Br2. Especially, the 1000 Ag QDs/Bi4O5Br2 composite exhibited the strongest photocatalytic ability with disinfecting all bacteria (1 × 107 cfu/mL) after 180 min visible light irradiation. The promoted photocatalytic ability of 1000 Ag QDs/Bi4O5Br2 mainly be attributed to the synergistic effect of SPR produced by Ag and the formation of Schottky barrier which facilitate the separation efficiency of charge carrier and light utilization. The mechanism of photocatalytic disinfection over the Ag QDs/Bi4O5Br2 composite was that the generated active species h+ (hole) and ·O2− (superoxide radical) disrupted the cell envelop to induce the leakage and decomposition of the cellular substances (e.g. protein, deoxyribonucleic acid (DNA) and potassium ion (K+)) as validated with the multiple techniques. This work open a new horizon to develop high-efficient BimOyXn-based photocatalytic disinfection materials.