Homogeneous magnetic Ag-Au alloy microparticles for ultrasensitive catalytic reduction of aromatic nitro compounds

Recyclable Mussel-Inspired Magnetic Nanocellulose@Polydopamine-Ag Nanocatalyst for Efficient Degradation of Refractory Organic Pollutants and Bacterial Disinfection

Development of a novel strategy to tackle bacterial-contaminated complex industrial wastewaters containing refractory organic pollutants is of great demand. In this study, polydopamine (PDA)-coated magnetic cellulose nanofiber (MCNF)-loaded silver nanoparticle (AgNP) (MCNF/PDA-Ag) nanocomposites were designed and applied for efficient degradation of organic dye pollutants and inactivation of Escherichia coli (E. coli) in wastewater. In the presence of NaBH₄, MCNF/PDA-Ag could achieve a high catalytic reduction rate of 6.54 min^-1 for the removal of methylene blue. Similarly, it showed good catalytic reduction performance for methyl orange (0.63 min^-1) and 4-nitrophenol (2.94 min^-1). The MCNF/PDA-Ag nanocomposites can be easily magnetically recycled and reused with negligible loss of catalytic performance. Moreover, this nanocatalyst also exhibited excellent disinfection performance against E. coli, with more than 99% disinfection ratio at very low doses (50 μg/mL). Overall, this work provides new insights into a delicate design of advanced magnetically recyclable silver nanocomposites with ultrahigh catalytic rates and excellent antibacterial properties from sustainable nature biomass.

Urchin-like hollow SiO2@γ-MnO2 microparticles for the rapid degradation of organic dyes

In this paper, using hollow silica microspheres as carriers, we developed a facile one-pot method for the preparation of hollow SiO2@MnO2 composite microparticles. Under a certain proportion of hollow silica microspheres and manganese salt, a novel kind of hollow urchin-like SiO2@γ-MnO2 microparticles was obtained. The structure and morphology of the composite microparticles were characterized by XRD, SEM and TEM. On this basis, using rhodamine B and methyl orange as model molecules, the oxidative degradation ability of the hollow SiO2@γ-MnO2 microparticles for organic dyes in water was investigated through UV-vis analysis technology. The urchin-like SiO2@γ-MnO2 microparticles showed excellent performance for the rapid oxidative degradation of organic dyes under acidic conditions. This study indicated that γ-MnO2 loaded on hollow materials can be used as an efficient tool for treating organic dye wastewater, and shows broad application prospects for solving environmental problems in the related industry.

Enhanced Catalytic Activity of Magnetic Bimetallic Ag-Au Nanoparticles Mediated by Surface Plasmon Resonance

We firstly discover the enhanced catalytic activity of magnetic noble metal nanoparticles mediated by surface plasmon resonance. Under light irradiation with certain wavelength, the catalytic performance of magnetic noble metal nanoparticles shows changes with different degrees and directions that are associated with the surface plasmon resonance (SPR) of the noble metal. Moreover, the coupling of silver and gold allows the catalytic performance of magnetic bimetallic Ag-Au nanoparticles to show more positive response to surface plasmon resonance. The magnetic bimetallic Ag-Au nanoparticles show excellent catalytic performance toward the reduction reaction of aromatic nitro group, and corresponding rate constant of the catalytic reduction reaction increases about three times with light irradiation.