Co-, Cu-substituted ZnAl ternary layered double hydroxides (LDHs) were synthesized and explored as efficient photocatalysts for dye degradation. LDH materials were fully characterized with various methods including elemental analysis, X-ray diffraction, infrared spectroscopy, Raman spectroscopy, and transmission electron microscopy, which revealed that LDH materials were well crystallized without any amorphous phase as impurity. In addition, the plates of LDH were well dispersed, one plate being easily distinguished from another plate, and their size could also be controlled by varying the Co, Cu substitution ratio. As an application, the adsorption characteristics and photocatalytic degradation of orange II, a model pollutant, were investigated. In particular, Co-substituted [a]

Co(2+) and Cu(2+) substituted MgAl layered double hydroxides with an M(2+)/M(3+) atomic ratio of 2.0 were synthesized by a co-precipitation method and fully characterized using various techniques including powder X-ray diffraction, ICP-AES analysis, FT-IR, DR UV-Vis spectroscopy, N2 adsorption-desorption and transmission electron microscopy. The materials revealed a good crystallinity with no phase impurity and successful substitution of cobalt and copper ions in the framework of binary LDH with the target ratio of metals in the sheet. The adsorption characteristics (kinetic and isotherm) and the catalytic oxidation of organic pollutants, methylene blue (cationic dye) and orange II (anionic) were carried out to investigate a potential use of LDH materials as catalysts. In particular, Co3Cu1Al2 LDH exhibited an excellent catalytic activity towards catalytic dye degradation, especially for orange II with good stability and reusability over several times. Furthermore, this LDH material showed good catalytic performance for several chlorophenol compounds, suggesting its practical application in wastewater treatment. Therefore, layered double hydroxides substituted with Co(2+) and Cu(2+) could be promising candidates in various applications, such as the abatement of organic pollutants.

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A model structure is proposed for the layered double hydroxide [Mg 2 Al(OH) 6 ] + • Cl-(Mg/Al ratio R = 2). The structural parameters of this model have been optimized by DFT calculations and both PXRD and vibrational spectra have been simulated. The comparison with experimental data confirms the validity of the model. Thanks to the synergy between experiment and theory it is now possible to analyze in detail the vibrational signals and understand the interactions between the different components of this material.