Journal of Sol-Gel Science and Technology https://doi.org/10.1007/s10971-018-4903-8 ORIGINAL PAPER: SOL-GEL, HYBRIDS AND SOLUTION CHEMISTRIES Novel route to synthesize CaAl- and MgAl-layered double hydroxides with highly regular morphology Szabolcs Muráth 1,2 ● Zoltán Somosi 1,2 ● Ákos Kukovecz 3 ● Zoltán Kónya 3,4 ● Pál Sipos 2,5 ● István Pálinkó 1,2 Received: 21 September 2018 / Accepted: 4 December 2018 © Springer Science+Business Media, LLC, part of Springer Nature 2018 Abstract A facile, sol–gel method was developed to obtain Al-containing layered double hydroxides (LDHs) with Ca or Mg divalent cations. Ca- and Al-alkoxide were added to aqueous NaNO 3 solution, and, after rapid gelation, a solid product, phase-pure, highly crystalline CaAl–LDH was formed with exceptionally regular morphology without impurities for the first time with sol–gel method. The lack of salt in the solution used for the hydrolysis resulted in a non-desirable by-product (katoite). For the sol–gel synthesis of MgAl–LDH, it was found that its formation was less sensitive to the presence of nitrate ions, and pure water or aqueous NaOH worked equally well. The product was also a highly crystalline material with thin, plate-like morphology as revealed by X-ray diffractometry and scanning electron microscopy. IR measurements indicate the lack of organic substance in the interlamellar space for both materials. Graphical Abstract Sol-gel process Co-precipitation from nitrates LDHs with better quality, higher crystallinity, high purity are obtained by sol-gel method MgAl–LDH: alkoxides + water/NaOH solution at room temperature CaAl–LDH: alkoxides + NaNO3 solution at room temperature Highlights ● A novel version of sol–gel synthesis was utilized to prepare two types of layered double hydroxides. ● The platelets have well-defined hexagonal morphology. ● The products have thin crystals with high aspect ratio. Keywords CaAl- and MgAl-layered double hydroxides ● Sol–gel process ● X-ray diffractometry and microscopic analysis ● Metal alkoxides ● Crystals with regular morphology * István Pálinkó palinko@chem.u-szeged 1 Department of Organic Chemistry, University of Szeged, Dóm tér 8, Szeged H-6720, Hungary 2 Materials and Solution Structure Research Group, Institute of Chemistry, University of Szeged, Aradi Vértanúk tere 1, Szeged H-6720, Hungary 3 Department of Applied and Environmental Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary 4 MTA-SZTE Reaction Kinetics and Surface Chemistry Research Group, Rerrich Béla tér 1, Szeged H-6720, Hungary 5 Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, Szeged H-6720, Hungary 1234567890();,: 1234567890();,: