The urea method for the direct synthesis of ZnAl layered double hydroxides with nitrate as the interlayer anion

ZnAl layered double hydroxides (LDHs) with nitrate as the charge balancing anion in the interlayer space were synthesized by precipitation from homogeneous solution using urea hydrolysis. The composition of the synthesis mixture and the synthesis time were varied in order to identify the parameters, which control if nitrate or carbonate will be the interlayer anion. Especially, the addition of ammonium nitrate turned out to be an effective tool for the synthesis of nitrate containing ZnAl LDHs independent from the synthesis time. Results are mainly based on powder X-ray diffraction measurements of the obtained samples.

Research highlights
► Direct synthesis of nitrate containing ZnAl LDHs by using the urea method.
► pH is key parameter to control if nitrate or carbonate will be interlayer anion.
► The method will enable easy anion exchange for the obtained large-crystal LDHs.