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

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

doi:10.1016/j.heliyon.2018.e00654

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

Heliyon. 2018 Jun 20;4(6):e00654. doi: 10.1016/j.heliyon.2018.e00654. eCollection 2018 Jun.

Authors

Wanghui Chen^{1

2}, Maxence Wilmet^{1

3}, Thai Giang Truong³, Noée Dumait³, Stéphane Cordier³, Yoshio Matsui², Toru Hara⁴, Toshiaki Takei⁵, Norio Saito^{1

2}, Thi Kim Ngan Nguyen^{1

2}, Takeo Ohsawa^{6

2}, Naoki Ohashi^{1

6

2}, Tetsuo Uchikoshi^{1

2}, Fabien Grasset^{1

2}

Affiliations

¹ CNRS-Saint Gobain, UMI 3629, Laboratory for Innovative Key Materials and Structures (LINK), National Institute of Material Science, 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan.
² Research Center for Functional Materials (RCFM), National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan.
³ Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) - UMR 6226, F-35000 Rennes, France.
⁴ Research Center for Structural Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan.
⁵ Research Network and Facility Services Division, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan.
⁶ NIMS-Saint-Gobain Center of Excellence for Advanced Materials, National Institute of Material Science, 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan.

Abstract

Hexanuclear tantalum bromide cluster units [{Ta₆Brⁱ₁₂}L^a₆] (i = inner, a = apical, L = ligand OH or H₂O) are embedded into SiO₂ nanoparticles by a reverse microemulsion (RM) based method. [{Ta₆Brⁱ₁₂}Br^a₂ (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.

Keywords: Materials chemistry; Materials science; Nanotechnology.