International audienceThis study reports the first integration of inorganic tantalum octahedral metal atom clusters into multifunctional nanocomposite coating materials and devices for window technology and energy saving applications. [Ta6Br12i](n+) (n = 2, 3 or 4) cluster-based high visible transparency UV and NIR filters are realized. Green and brown colored films are fabricated by coating on an indium-doped tin oxide glass substrate by electrophoretic deposition, an industrialized solution process. The efficiency in energy saving of the new UV-NIR filters was estimated by the determination of different figure of merit (FOM) values, such as Tvis, Tsol and Tvis/Tsol (Tsol = solar transmittance and Tvis = visible transmittance), and the color coordinates (x, y, z and L*a*b). The Tvis/Tsol ratio is equal to 1.25 for the best films. Such values are evidence of a higher energy saving efficiency than most of the inorganic composites reported in the literature. These promising results pave the way for the use of transition metal clusters as a new class of nanocoatings in energy saving window-based applications

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.

Transparent optical thin films for energy saving application have recently gained substantial prominence for functional window processes. In this study, highly visible transparent nanocomposite films with ultraviolet (UV) and near-infrared...

SiO2 coating on the surface of negatively charged polymer beads (n-PBs) succeeded in a typical stöber process with tetraethyl orthosilicate (TEOS). The core-shell structure of the resulting particles was confirmed by TEM observation and EDS mapping. Hollow SiO2 particles (HSPs) with monodisperse size and high dispersibility were further fabricated by calcining the obtained SiO2-coated n-PBs in air at 600 o C. Two advantages of using n-PBs for the fabrication of SiO2-coated polymer beads and HSPs were revealed as (1) lower cost with respect to positively charged polymer beads (p-PBs) and (2) improving the dispersibility of the obtained HSPs.According to our observations, there are two prerequisites for the formation of SiO2 shells on n-PBs, as (1) the high surface charge density of n-PBs and (2) low water concentration in reaction system.A mechanism was proposed for explaining the coating of SiO2 on the like-charged polymer beads.In that mechanism, the adsorption of NH4 + ions on the surface of n-PBs played a critical role for SiO2 coating, as it not only screened the surface charge of n-PBs to reduce the energetic barrier for