We report here an electrodeposition route for the preparation of oriented and well-defined ZnO nanostructures by kinetically controlling the growth rates of various facets of the deposit by appropriate capping agents. We demonstrated that adsorption of Cl(-) takes places preferentially onto the (0001) planes to hinder the crystal growth along the c-axis, and results in the formation of platelet-like crystals. It is also shown that the morphology evolved from hexagonal tapers to hexagonal rods and rhombohedral rods by changing the compositions of the capping agents. Furthermore, strong UV emissions at 380 approximately 390 nm and negligible green bands at around 500 nm were observed, indicating that these ZnO electrodeposits are highly crystallized and of excellent optical quality.

The metal-organic framework ZIF-8, which undergoes hydrolysis under hydrothermal conditions, is endowed with high water-resistance after a shell-ligand-exchange-reaction. The stabilized ZIF-8 retains its structural characteristics with improved application performances in adsorption and membrane separation.Metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) are an emerging class of nanoporous materials showing a wide range of potential applications, e.g. gas storage, molecular separation, chromatography, heterogeneous catalysis and smart sensoring. 1 Yet for most of the MOFs, one of the major drawbacks is their poor hydrothermal stability, which is clearly a limitation to their practical applications. 2 Development of novel MOF structures with high stability is an important research topic. 3,4 To date, only a few MOFs are reported to possess satisfactory hydrothermal stability, e.g. the ZIF (zeolitic imidazolate framework) family, 4 MIL (Matérial Institut Lavoisier) analogues 3b and some zirconium 3c-e and pyrazolate 3a based MOFs. On the other hand, from a practical point of view, post-enhancement of hydrothermal stability of the already existing MOF materials is a more attractive option and one of the most active research domains nowadays. 5 However along with improved stability, the application properties of the parent MOFs were usually impaired, e.g. considerable decrease of the specific surface area (SSA) after different post-treatments. 5b-d

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We present a two-step electrochemical deposition process to produce hierarchical ZnO nanostructures that involves the electrodeposition of ZnO crystals with different morphologies, followed by the electrochemical epitaxial growth of oriented nanorods on the surfaces of the primary ZnO nanostructures. A variety of hierarchical ZnO nanostructures, including 2-fold nanorod arrays on nanosheets, 6-fold nanorods on nanorods, and 6-fold nanoneedles on nanoneedles, were synthesized on a large scale. The hierarchical nanostructures obtained by this technique are pure and uniform in morphology. Furthermore, we demonstrate that the hierarchical ZnO nanostructure of nanorods on nanosheets provides a good candidate for photoanodes in dye-sensitized solar cells.

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Large-scale and highly oriented single-crystalline ZnO nanotubes on conductive glass substrates have been realized by a two-step solution approach, which involves the electrodeposition of oriented ZnO nanorods and subsequently coordination-assisted selective dissolution along the c-axis to form tubular structure caused by preferential adsorption of ethylenediamine (EDA) and OH- on different crystal faces. After dissolution in aqueous EDA solution for 10−15 h, the inner/outer wall surfaces of the obtained ZnO nanotubes are quite smooth and the wall thickness is uniform in ∼10−30 nm. Furthermore, a strong near-band gap ultraviolet stimulated emission at a wavelength of 389 nm with a half-maximum of 3 nm is observed at room temperature.

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