Decarbonating layered double hydroxides using a carbonated salt solution.

Layered double hydroxides (LDHs) intercalated with tunable anionic species are finding increasingly wide applications. While LDHs with intercalated CO anions (LDH-CO) are usually synthesized to achieve high crystallinity, the substitution of the intercalated CO with other desired anions is rather difficult because of the ultra-high affinity of CO to LDHs' main plates. Herein, we report a novel and facile method to overcome this difficulty. LDH-CO is decarbonated submerging in a carbonated NaCl solution with CO bubbling. Complete deintercalation of CO is achieved quickly without damaging the main plates, , the hydroxide layers, even in the case of MgAl-LDH-CO having the most stable CO anions. It is shown that carbonic acid HCO in the salt solution reacts with intercalated CO to form bicarbonate (HCO), which exhibits a much lower affinity to the main plates and thus is easily substituted by chloride ions (Cl) from the salt solution.