Chemical Growth and Photochromism of Silver Nanoparticles into a Mesoporous Titania Template

• Published in: Langmuir Vol. 26; no. 2; pp. 1199 - 1206
• Main Authors: Bois, Laurence, Chassagneux, Fernand, Battie, Yann, Bessueille, François, Mollet, Laurent, Parola, Stéphane, Destouches, Nathalie, Toulhoat, Nelly, Moncoffre, Nathalie
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 19-01-2010
• Subjects: Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Materials: Nano-and Mesostructured Materials, Polymers, Gels, Liquid Crystals, Composites; Optics; Photochemistry; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Physics; Porous materials; Surface physical chemistry; Atomic force microscopy; Binary compound; Discoloration; Photochromism; Growth; Film; Nanoparticle; Backscattering; Porous material; Silica; Formaldehyde; Template; Chemical reduction; Nanocrystal; Elaboration; Scanning electron microscopy; Transition element compounds; Transition metal; Aldehyde; Surface plasmon; X ray diffraction; Mesoporosity; Substrate; Silver; Transmission electron microscopy; Chemical treatment; Resonance; Titanium oxide; Photooxidation
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la902339j

Elaboration of mesoporous titanium oxide film supporting silver nanoparticles is described. Mesoporous titanium oxide films are characterized by TEM analysis. Titania films are infiltrated with a silver salt solution and chemical reduction treatments are performed using either a NaBH4 or a formaldehyde solution. Infiltrated films are then characterized by TEM, SEM, AFM, UV−visible spectroscopy, X-ray diffraction, and Rutherford Backscattering Spectrometry (RBS). The utilization of a mesoporous titania substrate allows to control the nanoparticle size and the interparticle distance. RBS experiments provide the evidence that NaBH4 treatment induces a strong accumulation of silver nanoparticles in the subsurface of the layer, while formaldehyde treatment induces the formation of silver nanoparticles embedded into almost the whole depth of the titania film. Large silver nanocrystals are also formed at the film surface whatever the reducer used. A broad visible absorption band related to the surface plasmon resonance (SPR) is obtained in both cases and is strongly red-shifted compared to the SPR obtained for silver nanoparticles inside a silica matrix. Moreover, irradiation with visible light causes the photooxidation of silver nanoparticles by titania and a complete discoloration of the material. The photooxidation is related to a drastic decrease in the silver nanoparticle size and is found to be reversible, particularly in the case of the material obtained by the formaldehyde reduction.