Embedding hexanuclear tantalum bromide cluster {Ta6Br12} into SiO2 nanoparticles by reverse microemulsion method

• Main Authors: Wanghui Chen, Maxence Wilmet, Thai Giang Truong, Noée Dumait, Stéphane Cordier, Yoshio Matsui, Toru Hara, Toshiaki Takei, Norio Saito, Thi Kim Ngan Nguyen, Takeo Ohsawa, Naoki Ohashi, Tetsuo Uchikoshi, Fabien Grasset
• Format: Article
• Language: English
• Published: Elsevier 2018-06-01
• Series: Heliyon
• Subjects: Materials chemistry; Materials science; Nanotechnology
• Online Access: http://www.sciencedirect.com/science/article/pii/S2405844018302779
• ISSN: 2405-8440

Hexanuclear tantalum bromide cluster units [{Ta6Bri12}La6] (i = inner, a = apical, L = ligand OH or H2O) are embedded into SiO2 nanoparticles by a reverse microemulsion (RM) based method. [{Ta6Bri12}Bra2 (H2O)a4]·nH2O (noted TBH) and tetraethyl orthosilicate (TEOS) are used as the starting cluster compound and the precursor of SiO2, respectively. The RM system in this study consists of the n-heptane (oil phase), Brij L4 (surfactants), ethanol, TEOS, ammonia solution and TBH aqueous sol. The size and morphology of the product namely {Ta6Br12}@SiO2 nanoparticles are analyzed by HAADF-STEM and EDS mappings. The presence and integrity of {Ta6Br12} in the SiO2 nanoparticles are evidenced by EDS mapping, ICP-OES/IC and XPS analysis. The optical properties of {Ta6Br12}@SiO2 nanoparticles are analyzed by diffuse reflectance UV-vis spectroscopy, further evidencing the integrity of the embedded {Ta6Br12} and revealing their oxidation state. Both {Ta6Br12}2+ and {Ta6Br12}3+ are found in SiO2 nanoparticles, but the latter is much more stable than the former. The by-products in this RM-based synthesis, as well as their related factors, are also discussed.