New Insight into the Hierarchical Microsphere Evolution of Organic Three-Dimensional Layer Double Hydroxide: The Key Role of the Surfactant Template.

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Surfactants have proven a suitable template agent for the construction of organic three-dimensional layered double hydroxide (O3D-LDH) due to the excellent self-assembled property and ready operation. Although the morphology and growth of O3D-LDH are affected by various factors (initial surfactant concentration, Mg/Al molar ratio, hydrothermal temperature, urea concentration, hydrothermal time, etc.), little is known about the key role of surfactants in the growth behavior and mechanism. In this study, sodium dodecyl sulfate (SDS) was chosen to identify the behavior of the surfactant on the evolution of O3D-LDH with various factors. The as-grown procedure was investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and Brunauer-Emmett-Teller analysis. The results demonstrated that the ideal 3D roselike hierarchical structure was obtained at a Mg/Al/urea molar ratio of 2:1:10 and SDS concentration of 0.1 mol L-1 at 150 °C for 6 h. It is worth noting that SDS showed an extraordinary importance regarding the material growth, as it was intrinsically related to the formation of spherical micelles and functioned as an intercalating anion. Furthermore, a possible growth mechanism was proposed to explain the formation of O3D-LDH. Our finding opens a new insight into the role of SDS in the O3D-LDH fabrication and provides a theoretical foundation for other LDH material construction.