In this study, a systematic approach was applied to the hydrothermal synthesis of Zn 2 SnO 4 (ZTO) nanocrystals to gain insight into the fundamental factors controlling phase composition, particle size, crystal morphology and photocatalytic activity. The influence of various operating conditions, such as reaction temperature, alkaline concentration, duration time, and additive surfactants on the treatment process were investigated. By combining the results of X-ray diffraction (XRD), electron microscopy (SEM/TEM/ED/HRTEM), Raman and FT-IR spectroscopy, a complete structural and morphological characterization of the products was performed. The results indicated that the phase transformation probably evolved via a "dissolution-recrystallization" mechanism and accompanying the "Ostwald ripening" process. Furthermore, a correlation between the photocatalytic activity in the UV photodegradation of MB solutions and the particle properties was established.

ZSM-5 zeolites, Ga modified via different methods (in situ hydrothermal synthesis, mechanical mixing, incipient wetness impregnation, solid-state ion exchange, and liquid phase ion exchange), were systematically investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), 29Si, 27Al, and 71Ga magic-angle spinning (MAS) NMR, and H2 temperature-programmed reduction (H2-TPR). It is important to prove that both impregnation and liquid phase ion exchange could facilitate the incorporation of Ga species into the framework in addition to in situ hydrothermal synthesis. The liquid phase ion exchange method drove part of the Ga species into the framework, and it was further migrated into the framework by drying, while the incipient wetness impregnation method promoted part of the Ga species into the framework only during the calcination process. In the n-heptane catalytic aromatization procedure on the fixed bed, Ga modified ZSM-5 by in situ hydrothermal synthesis showed the highest benzene, toluene, ethylbenzene and xylene (BTEX) selectivity, owing to the increased strong Lewis acidic sites and mesopore volumes induced by the framework Ga species.

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The transformation from NaA (LTA) to MCM-49 (MWW) zeolite was achieved in the synergism of hexamethyleneimine (HMI), NaOH, and SiO2, in spite of no common composite build units between LTA (lta, sod, and d4r) and MWW (mel and d6r) structure. NaA (SiO2/Al2O3 = 2.0) was employed as the parent zeolite. The samples prepared at different crystallization stages were characterized by XRD, SEM, 29Si/27Al/13C MAS NMR, and STEM-EDS to investigate the intermediates during the transformation from NaA to MCM-49. As shown in SEM and STEM-EDS images, MCM-49 was proposed to be transformed gradually from the exterior to the interior of NaA, which was clearly observed by the core (LTA, low SiO2/Al2O3)–shell (MWW, high SiO2/Al2O3) coexisting zeolites as intermediates. With high relative crystallinity and the uniform sizes of crystals, the final MCM-49 was featured by Si enrichment on the external surface, which was proved by the shell (SiO2/Al2O3 = 45.4) wrapping around the core (SiO2/Al2O3 = 22.0). For transformed H-MCM-49 zeolite, the uniform sizes of crystals and the increase of total acid sites contributed to better accessibility of active centers, which achieved simultaneous improvement in ethylene conversion and ethylbenzene selectivity in the liquid-phase alkylation of benzene with ethylene.

Fabrication and characterization of the miniature device of waveguide grating-structures (WGS) on the end facet of an optical fiber are demonstrated. A layer of ZnO between the fiber and the grating structures serves as the waveguide. The fiber is used to direct the excitation light to the WGS and to carry the signal response back to the detection system. The narrow-band waveguide resonance mode tunable in the visible spectrum can be measured through the fiber in both the transmission and reflection. This nanodevice may be suitable as long-range sensors for the detection of refractive-index changes in nontransparent or toxic liquids.

The oriented growth of the hydroxyapatite (HAp) nanorod array on the glass substrate with a ZnO seed layer was investigated. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. The HAp nanorods have a length of about 2 µm and a diameter of about 200 nm. The growth mechanism of the (0001)-oriented HAp nanorod array was attributed to the "mold effect" of the (0001)-oriented ZnO seed layer. The dissolution characteristics of the as-prepared HAp nanorod array have also been investigated.

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