Effect of Al substrate microstructure on layered double hydroxide morphology

Abstract

Layered double hydroxides (LDHs) are 2D ionic lamellar nanomaterials, which attract increasing interest for applications in different fields. This paper shows that their morphology is strongly affected by the microstructure of the substrate on which they grow. Zn-Al LDHs were grown in the same conditions on Al substrates with different microstructural features obtained from cold-rolled sheets by annealing at 265°C for increasing soaking time up to 1 h. LDH morphology was then investigated through scanning electron microscopy observations. The homogeneous distribution of petals on the substrate surface mainly depends on grain size distribution. A bimodal grain size distribution in the substrate leads to the formation of petal clusters and a not complete covering of the surface. In the case of grains of large size the nucleation sites are the dislocations forming the walls of the cells, while owing to their low density, the dislocations inside the grains are not a relevant factor in determining the LDH morphology.

Synergistic MXene/LDH heterostructures with extensive interfacing as emerging energy conversion and storage materials

“…Several comprehensive reviews about the detailed synthesis of LDHs are available; hence, we briey describe the primary methods to prepare pristine LDHs. [104][105][106][107][108] The synthetic methods could primarily be grouped into direct and indirect methods.…”

“…Several comprehensive reviews about the detailed synthesis of LDHs are available; hence, we briefly describe the primary methods to prepare pristine LDHs. 104–108 The synthetic methods could primarily be grouped into direct and indirect methods. Coprecipitation, electrochemical, hydrothermal, salt oxide, and sol–gel processes are the main strategies for direct synthesis, while post-treatments such as anion exchange, reconstruction, and delamination are known indirect synthetic methods.…”

Status and Challenges in Biomedical Applications of LDHs

“…2 schematically illustrates these typologies. In the past we have already grown LDH (Zn,Al) nanostructures on Al sheets [1][2] using in situ growth. The nutrient solution used was composed, in a 1:1 ratio, of zinc chloride (ZnCl2) and, for pH control, hexamethylenetetramine (C6H12N4) in a 5 mM concentration.…”

Upscaling the urea method synthesis of CoAl layered double hydroxides

“…Usually, LDHs are obtained by different synthesis procedures such as co-precipitation [25], hydrothermal synthesis [13], sol-gel methods [26], mechanochemistry [27], or the epoxide route [28], to name a few [29]. Among them, hydrothermal methods based on ammonium-releasing reagents (ARRs), commonly urea or hexamethylenetetramine, are especially interesting since they allow one to obtain large and highly crystalline particles [30][31][32].…”