An alternative route to polyoxometalate-exchanged layered double hydroxides: the use of ultrasound

摘要

Layered double hydroxides (LDHs) have the general formula [M_(1-x)~(II)M_x~(IIII) (OH)2]A_(x)~(n-)·mH2O, where M~(II) = Mg, Ni, Zn, . . ., M~(III) = Al, Cr, Fe, . . ., and A=CO_3~(2-), NO_3~-, SO_4~(2-), Cl~-, etc. Their structure consists of brucite-like layers positively charged by the substitution of trivalent cations by divalent cations. Electroneutrality is attained by exchangeable anions in the interlayer space. Interlayer water is also present [1], Considerable interest has been shown in LDHs recently as a result of their role in different industrially relevant processes, particularly as potential catalysts and catalyst precursors [1].