Plasmon-assisted degradation of methylene blue with Ag/AgCl/montmorillonite nanocomposite under visible light

• Ag/AgCl–MMT nanocomposite was synthesis by dispersion method and light irradiation.
• Montmorillonite play important role in stability of nanocomposite for photocatalysis.
• The optimal amount of photocatalyst is very low about 0.09 g/L.
• The band gap for AgCl in nanocomposite is 3.7 eV, but it is active under visible light.
• The surface plasmon resonance of Ag nanoparticles on AgCl makes it active in visible region.

Metal–semiconductor compounds, such as Ag/AgX (X = Cl, Br, I), enable visible light absorption and separation of photogenerated electron–hole through surface plasmon resonance (SPR) effect. However, the electron–hole generated and separated by light are vulnerable in Ag/AgX phase because of the occurrence of secondary recombined. In order to more effectively utilize the SPR photocatalytic effect, nanoparticles are located in a matrix. In this article, Ag/AgCl nanoparticles were synthesized in montmorillonite (MMT) matrix using dispersion method and light irradiation. The structure, composition and optical properties of such material were investigated by transmission electron microscopy (TEM), UV–visible diffuse reflectance spectroscopy (UV–Vis DRS), X-ray diffraction (XRD) and FTIR. Powder X-ray diffraction showed intercalation of Ag/AgCl nanoparticles into the clay layers. The as-prepared plasmonic photocatalyst exhibited an enhanced and stable photoactivity for the degradation of methylene blue (MB) under visible light. The high activity was attributed to the surface plasmon resonance (SPR) exhibited by Ag nanoparticles on the surface of AgCl. The detection of reactive species by radical scavengers displays that O2− and OH− are the main reactive species for the degradation of MB under visible light irradiation. The studies showed that 20 min illumination under visible light can complete degradation of methylene blue (MB), and indicate a high stability of photocatalytic degradation. The mechanism of separation of the photo-generated electrons and holes at the Ag/AgCl–MMT nanocomposite was discussed.

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