Ionic conductivity of microporous titanosilicate ETS-10 and ion-exchanged Mn+-ETS-10 (where, Mn+ = Li+, Na+, Mg2+, Zn2+, Ca2+) thin films prepared by secondary growth method

Impedance spectroscopy was used to investigate the long-range ionic conductivity of the microporous, titanosilicate (Na,K)-ETS-10 and ion-exchanged Mn+-ETS-10 (where, Mn+ = Li+, Na+, Mg2+, Zn2+, Ca2+) thin films prepared by secondary growth method. To figure out the effect of grain boundary on ionic conduction, as-synthesized (Na,K)-ETS-10 films possessing different thicknesses of columnar grain structure (i.e., films prepared via 4h-, 6h-, 8h-, and 10h-growth) were tested. The conductivities of the films with different thicknesses at 723 K were in the range of similar to 10(-3) Omega(-1)cm(-1). However, activation energies of the films decreased from 52.8 to 47.3 kJ mol(-1) (i.e., 0.6 to 0.5 eV) for 4h-(Na,K)-ETS-10 to 10h-(Na,K)-ETS-10 films, respectively. The as-synthesized (Na,K)-ETS-10 film prepared via 6h-growth (denoted as (Na,K)-6h-ETS-10) and monovalent cation-exchanged samples Li- and Na-6h-ETS-10 films exhibit conductivities of 2.1 x 10(-3), 2.4 x 10(-4), and 2.7 x 10(-4) Omega(-1)cm(-1), respectively, at 723 K and activation energies of 50.1, 55.5, and 55.4 kJ mol(-1), respectively, in the temperature range 573-773 K. Divalent cation-exchanged samples Mg-, Zn- and Ca-6h-ETS-10 films exhibit conductivities of 2.3 x 10(-4), 2.9 x 10(-4), and 8.8 x 10(-5) Omega(-1)cm(-1), respectively, at 723 K and activation energies of 62.5, 57.9, and 65.2 kJ mol(-1), respectively, in the temperature range 573-773 K. The data shown here indicate that ionic conductivity of intergrown (Na,K)-ETS-10 films prepared by secondary growth method were significantly enhanced with respect to pressed pellets of powder zeolite and zeo-type materials which imply the importance of engineering the microstructure of the zeolite film to improve the conductivity of zeolites and zeo-type materials

Secondary Growth of Microporous Vanadosilicate AM 6 Films

Oriented vanadosilicate AM-6 thin films with an average thickness of 1-2 mu m were prepared on the ITO coated glass substrates using secondary growth method with a partial a(b)-out-of-plane preferred crystal orientation for the first time. In secondary growth method, titanosilicate ETS-10 crystals were deposited on the substrate from a colloidal suspension to form seed layers. Then, the hydrothermal growth of the seed crystals was conducted to form AM-6 films. It was observed that the AM-6 films formed possess similar 1-D VO3 (2-) quantum wires as also observed in powder AM-6 crystals. Afterward, the effect of reaction temperature and amount of water in the secondary growth gel on crystal morphology and a(b)-out-of-plane crystallographic preferred orientation (CPO) were investigated to gain a better understanding of the secondary growth mechanism of vanadosilicate AM-6 films. The results suggested that the increased amount of water leads to increased CPO in the AM-6 films, whereas an increase in reaction temperature from 503 to 528 K leads to more c-oriented AM-6 films with a decreased CPO value. Furthermore, an increase in the reaction temperature led to a decrease in the reaction time, resulting in the formation of quartz impurity. Accordingly, well intergrown a(b)-out-of-plane oriented vanadosilicate films were grown for the first time using ETS-10 seed crystals and it is believed that this work provides an effective pathway for controlling the synthesis of AM-6 films expanding the possible range of applications of these materials possessing 1-D quantum wires

Secondary growth of microporous vanadosilicate AM-6 films

Oriented vanadosilicate AM-6 thin films with an average thickness of 1-2 mu m were prepared on the ITO coated glass substrates using secondary growth method with a partial a(b)-out-of-plane preferred crystal orientation for the first time. In secondary growth method, titanosilicate ETS-10 crystals were deposited on the substrate from a colloidal suspension to form seed layers. Then, the hydrothermal growth of the seed crystals was conducted to form AM-6 films. It was observed that the AM-6 films formed possess similar 1-D VO3 (2-) quantum wires as also observed in powder AM-6 crystals. Afterward, the effect of reaction temperature and amount of water in the secondary growth gel on crystal morphology and a(b)-out-of-plane crystallographic preferred orientation (CPO) were investigated to gain a better understanding of the secondary growth mechanism of vanadosilicate AM-6 films. The results suggested that the increased amount of water leads to increased CPO in the AM-6 films, whereas an increase in reaction temperature from 503 to 528 K leads to more c-oriented AM-6 films with a decreased CPO value. Furthermore, an increase in the reaction temperature led to a decrease in the reaction time, resulting in the formation of quartz impurity. Accordingly, well intergrown a(b)-out-of-plane oriented vanadosilicate films were grown for the first time using ETS-10 seed crystals and it is believed that this work provides an effective pathway for controlling the synthesis of AM-6 films expanding the possible range of applications of these materials possessing 1-D quantum wires

Effect of ion-exchange on structural, electronic, and vibrational properties of the-O-Ti-O-Ti-O-quantum wires in ETS-10

5siThe exchange of the extra-framework Na+ ions in Engelhard titanosilicate (ETS-10) with Ag+ and Ru3+ has been investigated theoretically by means of density functional theory (DFT) and experimentally, with the aim of elucidating its effects on the structural, electronic and vibrational properties of the Ti-O-Ti quantum wire. A comparison of theoretical findings and experimental Raman data in the region of Ti-O-Ti stretching reveals that the introduction of the Ag+ ions preserves the integrity of the wire to a large extent while Ru3+ ions cause large-scale distortions along with some loss in crystallinity.nonenoneKoç, Mehmet; Galioglu, Sezin; Toffoli, Daniele; Üstünel, Hande; Akata, BurcuKoç, Mehmet; Galioglu, Sezin; Toffoli, Daniele; Üstünel, Hande; Akata, Burc

Understanding the Effects of Ion-Exchange in Titanosilicate ETS-10: A Joint Theoretical and Experimental Study

Density functional theory (DFT) calculations within the gradient-corrected approximation (GGA) were carried out on two models of Engelhard titanosilicate (ETS-10) with the aim to elucidate the effect of ion exchange on the structural and electronic properties of the TiOTi quantum wire. The partial and full exchange of Na+ cations with alkaline, earth-alkaline, and transition metal ions have been investigated. The theoretical results have been complemented by experimental X-ray diffraction (XRD) and Raman data in the region of the TiOTi stretching of the wire. Overall, the experimental data support the theoretical findings where substitution of Na+ with K+, Ag+, and Ca2+ cause only minor structural changes in the wire while the inclusion of Zn2+, Ru3+, and Au3+ cause its partial or entire disruption

Effect of silver encapsulation on the local structure of titanosilicate ETS-10

Silver(0) nanoparticles stabilized by titanosilicate (ETS-10) framework were synthesized by following a simple two step procedure involving the incorporation of silver(I) (Ag+) ions into ETS-10 matrix via ion-exchange with extra framework Na+ and K+ cations followed by their reduction with sodium borohydride (NaBH4) in aqueous medium all at room temperature. Silver(0) nanoparticles dispersed in the ETS-10 matrix were collected as gray powders and characterized by using advanced analytical methods including ICP-OES, P-XRD, XPS, FE-SEM, TEM, HR-TEM, DR-UV-vis, Raman spectroscopies and N-2 adsorption-desorption technique. Overall result shows the formation of silver(0) nanoparticles dispersed within the framework of ETS-10 without causing alteration in ETS-10 lattice and mesopore formation. The changes in the local titanate (TiO32-) structure of ETS-10 resulting from the incorporation of silver(I) ions and formation of silver(0) nanoparticles within the titanosilicate (xTiO(2) (1 - x)SiO2) framework were extensively studied on silver(I)-exchanged and silver(0) nanoparticles containing samples, separately. Although maintaining of structural integrity of host material had been monitored for silver(I)-ETS-10, detailed Raman analyses of silver(0)-ETS-10 samples showed significant changes in the titanate quantum wires of ETS-10 framework depending on the silver loading. Total collapse of these units was observed in the silver(0)-ETS-10 samples with high silver loading (15 wt.% silver(I)). Moreover, the catalytic application of silver(0)-ETS-10 was demonstrated in the aerobic oxidation of diphenyl carbinol to benzophenone, which showed that silver(0)-ETS-10 is a highly active and selective catalyst in this reaction. Additionally, they were found to be highly stable catalyst for this transformation