**Preface to "Layered Double Hydroxides (LDHs)"**

Their exceptional characteristics and uniqueness make Layered Double Hydroxides (LDHs) and their derivatives promising two-dimensional layered materials that are suitable for several existing and future applications in diverse fields. To name a few, we can mention environmental monitoring and preservation, biotechnology, pharmaceutical and chemical processes, the design and realization of new functional polymers and new magnetic materials with a high-saturation magnetic field, and new composite materials for sustainable concrete infrastructure.

The number of research and review articles in high-impact journals highlights the growing attention paid to these materials by not only academic, but also applied-science researchers. This is due to the peculiar properties of LDHs, such as their ease of synthesis even on a large scale, their chemical and thermal stability, their uniform distribution of metal cations, and their ability to intercalate anionic species within the interlayer space and possibly release them, together with their high biocompatibility.

This growing interest has led to a parallel growth in the number of publications, some of which appear in this Special Issue of *Crystals*, presenting both research and review papers. In particular, deeper attention has been paid to innovative synthesis techniques, focusing on those with a low environmental impact, to applications for renewable energy sources, and to interlayer anions' exchange capability for drug release. The ability of Layered Double Hydroxides to form hybrid inorganic/organic nanomaterials is stressed in the review articles.

We are confident that reading the articles published in this Special Issue, written by accomplished researchers working for years in the field, will be a source of inspiration to any scientist who studies LDHs within any discipline.

> **Roberto Pizzoferrato, Maria Richetta** *Editors*
