This review surveys recent advances in the applications of layered double hydroxides (LDHs) in heterogeneous catalysis. By virtue of the flexible tunability and uniform distribution of metal cations in the brucite-like layers and the facile exchangeability of intercalated anions, LDHs-both as directly prepared or after thermal treatment and/or reduction-have found many applications as stable and recyclable heterogeneous catalysts or catalyst supports for a variety of reactions with high industrial and academic importance. A major challenge in this rapidly growing field is to simultaneously improve the activity, selectivity and stability of these LDH-based materials by developing ways of tailoring the electronic structure of the catalysts and supports. Therefore, this Review article is mainly focused on the most recent developments in smart design strategies for LDH materials and the potential catalytic applications of the resulting materials.

Fabricating active materials into specific macrostructures is critical in the pursuit of high electro-catalytic activity. Herein we demonstrate that a three-dimensional (3D) architecture of NiFe layered double hydroxide (NiFe-LDH) significantly reduced the onset potential, yielded high current density at small overpotentials, and showed outstanding stability in electrochemical oxygen evolution reaction.

In particle formation, the method can be just as important as the chemical reaction involved. A new method of synthesizing hydrotalcite-like layered double hydroxides (LDHs) of the type [Mg1 - x Al x (OH)2] x +(CO3 2-) x/ 2·yH2O (x = 1.7−3.3) is reported. The key features of this method are a very rapid mixing and nucleation process in a colloid mill followed by a separate aging process. The properties of the resulting LDHs are compared with those of materials produced using the conventional coprecipitation process at constant pH. The compositions and structural parameters of the materials synthesized using the two routes are very similar, although the crystallinity is slightly higher for the LDHs produced using the new method. The thermal behavior of the materials synthesized using the two routes is also similar. The major advantage of the new method is that it affords smaller crystallites with a higher aspect ratio, having a very narrow distribution of crystallite size. In the conventional coprecipitation process at constant pH, the mixing process takes considerable time such that nuclei formed at the beginning of the process have a much longer time to undergo crystal growth than those formed at the end of the process. The consequence is that a wide dispersion of crystallite sizes is obtained. In the colloid mill process, however, the mixing and nucleation are complete in a very short time and are followed by a separate aging process. Furthermore, we suggest that the extreme forces to which the nucleation mixture is subjected in the colloid mill prevent aggregation of the nuclei and result in the nuclei having a uniform small size. When the resulting mixture is aged in a separate process, well-formed crystallites with a similarly narrow range of diameters result.

The one- and two-photon luminescence of stilbene-type solid-state materials can be tuned and controlled from blue to yellow color by a supramolecular cocrystal method.