Issue 30, 2024

Insight into the synthesis of LDH using the urea method: morphology and intercalated anion control

Abstract

Layered double hydroxides (LDHs) are a class of layered solids applied in many application fields. The study of synthetic methods able to control the interlayer composition and morphology of LDH is an open issue. The urea method, which exploits the thermal decomposition of urea, is known for yielding highly crystalline LDH in the carbonate form. This form is highly stable and, to replace carbonate ions with more easily exchangeable anions, a second step is required. In this work, we modified the urea method to obtain MgAl and ZnAl LDH in the chloride or nitrate form through a one-step synthesis. The effects of the urea/(Al + M(II)) molar ratio (R), reaction time and metal salt concentrations were deeply investigated. We found that LDH in chloride and nitrate forms can be prepared from solutions of metal salts not exceeding 1 M by adjusting R and maintaining the reaction time at 48 hours. The morphology of these products was found to depend on the R value and on the metal salts used in the synthesis. A high R value and nitrate salts favoured the formation of sand-rose crystals, while chloride salts induced the formation of plate-like crystals. The crystal growth mechanism and the parameters influencing the morphology are discussed with reference to ZnAl LDH by monitoring the synthesis over time.

Graphical abstract: Insight into the synthesis of LDH using the urea method: morphology and intercalated anion control

Supplementary files

Article information

Article type
Paper
Submitted
24 Maijs 2024
Accepted
02 Jūl. 2024
First published
03 Jūl. 2024
This article is Open Access
Creative Commons BY license

Dalton Trans., 2024,53, 12543-12553

Insight into the synthesis of LDH using the urea method: morphology and intercalated anion control

A. Di Michele, E. Boccalon, F. Costantino, M. Bastianini, R. Vivani and M. Nocchetti, Dalton Trans., 2024, 53, 12543 DOI: 10.1039/D4DT01529K

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