▎ 摘　　要

Silver nanoparticle (Ag NPs) and their nanocomposite materials have been widely applied as catalysts and disinfectants for wastewater treatment. However, most reported Ag NP-based nanocomposites possess a low loading of Ag NPs, which require a high dosage to achieve satisfactory catalytic decontamination performance to organic pollutants and good disinfection to the bacteria. Herein, we synthesize a novel Ag NPs nanocomposite with an extremely-high loading of Ag NPs (up to 30 wt%) via tannic acid (TA)/Fe3+ complexation by using magnetic graphene oxide (MGO). The Ag@MGO-TA/Fe3+ catalyst shows excellent stability in aqueous environment and can achieve an ultrahigh catalytic reduction rate of 0.054 s(-1) for methylene blue (MB) at an extremely low dosage (i.e., 0.05 mg/mL), which is about ten times higher than that of most NPs-based catalysts reported previously under similar condition. Moreover, the magnetic nanocomposites can be easily regenerated and are highly recyclable without any obvious performance loss. In addition, the novel Ag@MGO-TA/Fe3+ nanocomposites exhibit disinfection performance against Escherichia coli (E. coli) with similar to 100% killing efficacy at a very low dosage (i.e., 20 mu g/mL). This work provides new insights into the rational design of advanced recyclable NP-based nanomaterials with ultrahigh catalytic rate and outstanding antimicrobial performance for water treatment and various environmental engineering applications.