# Stability Trends in Mono-Metallic 3d Layered Double Hydroxides

^{1}

^{2}

^{3}

^{*}

## Abstract

**:**

## 1. Introduction

_{2}capture [5,6], templating for oriented synthesis [7], photocatalysis [5,8], supercapacitance [9], membrane fabrication [10], and drug delivery [11,12]. LDHs are usually composed of divalent or trivalent metals with a general formula of $\left[\right({\mathrm{M}}_{1-x}^{\mathrm{II}}{\mathrm{M}}_{\mathrm{x}}^{\mathrm{III}}{{\left(\mathrm{OH}\right)}_{2}]}^{\mathrm{x}+}:\left({\mathrm{A}}_{\mathrm{x}/\mathrm{m}}^{\mathrm{m}-}\right)\xb7\mathrm{n}{\mathrm{H}}_{2}\mathrm{O};$ x = ~0.2–0.4, where the M

^{II}and ${\mathrm{M}}^{\mathrm{III}}$ can be either identical or different metallic ions. The LDH layers are positively charged and neutralised by anionic intercalants (A

^{m−}). Carbonate [13,14,15,16,17], nitrate [18], sulphate [13,16], and lactate [19] are some examples of the anionic intercalants in LDHs that compensate the positive charge of the LDH layers [20]. Recent studies suggest that the intercalant anions play a crucial role in determining the physicochemical properties of the final LDHs, opening the possibility of engineered LDHs for specific applications [21]. Therefore, understanding how guest anions influence the structural and electronic properties in LDHs is essential for tailoring their properties.

_{2}Al(AlSi)O

_{2}(OH)

_{10}·2.25H

_{2}O) [16], and hydrotalcite (Mg

_{0.7}Al

_{0.3}(OH)

_{2}(CO

_{3})

_{0.15}·0.63H

_{2}O) [22,23] were experimentally investigated and reported. Lactate as another intercalant anion is utilised in the intercalation of Fe LDH interlayers, showing a potential application in the design of catalytically active material for ${\mathrm{H}}_{2}$ production [19]. Most of the presented examples from the literature are for bimetallic LDHs. Monometallic LDHs are rarely studied and investigated in detail due to their lower stability and synthesis difficulties [24]. In particular, producing and maintaining both divalent or trivalent cations of the same metal in the application medium is challenging [25]. Furthermore, the difficulty in differentiating the divalent and trivalent cations of the same metal is a major characterisation drawback for monometallic LDHs. Consequently, bimetallic and trimetallic LDHs have become the most common in many applications [26,27].

## 2. Settings and Models

^{−1}spacing was used for integration over the Brillouin zone throughout all geometry optimisations. This spacing produced a $5\times 5\times 5$ grid for un-intercalated LDH compounds. The density of states was calculated with a 10-times-denser grid. During the geometry optimisation [35], performed with fixed basis quality, internal coordinates and lattice parameters were relaxed to forces smaller than 0.01 eV Å

^{−1}and energies smaller than 10

^{−5}eV. When a supercell contained more than one magnetic ion, both ferromagnetic and antiferromagnetic spin alignments were examined, and the lowest energy configuration was used. Using true magnetic ground state is critical for obtaining realistic geometries and total energies [36].

## 3. Results and Disscussion

_{B}, indicating a d

^{5}electronic occupation, which corresponds to the $+2$ oxidation state and high spin configuration, arranged as filled spin-up ${t}_{2g}$ and ${e}_{g}$ orbitals and empty spin-down ${t}_{2g}$ and ${e}_{g}$ orbitals. The Fe magnetisation was calculated to be 3.80 ${\mu}_{B}$, which corresponds to the high spin configuration of d${}^{6}$ occupation (${t}_{2g}^{3}$↑${e}_{g}^{2}$↑${t}_{2g}^{1}$↓${e}_{g}^{0}$↓). The Co magnetisation was calculated to be 0.94 ${\mu}_{B}$, indicating that, unlike Mn and Fe, $C{o}^{2+}\left({d}^{7}\right)$ is at a low-spin configuration of ${t}_{2g}^{3}$↑${t}_{2g}^{3}$↓${e}_{g}^{1}$↑${e}_{g}^{0}$↓. One should note that the calculated magnetisations are slightly smaller than nominal values of pure ionic bonds—by a fraction of 1 ${\mu}_{B}$. This trend indicates that the TM-O bonds slightly deviate from pure ionicity towards covalency [41].

_{2}]

_{2}:CO

_{3}, the magnetisation of both Fe ions was 4.21 ${\mu}_{B}$, indicating that both Fe ions were at +3 oxidation state. The stability trend was examined by calculating the decomposition enthalpy according to the following equations:

## 4. Conclusions

## Supplementary Materials

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## References

- Doustkhah, E.; Ide, Y. Bursting Exfoliation of a Microporous Layered Silicate to Three-Dimensionally Meso-Microporous Nanosheets for Improved Molecular Recognition. ACS Appl. Nano Mater.
**2019**, 2, 7513–7520. [Google Scholar] [CrossRef] - Doustkhah, E.; Ide, Y. Microporous layered silicates: Old but new microporous materials. New J. Chem.
**2020**, 44, 9957–9968. [Google Scholar] [CrossRef] - Doustkhah, E.; Assadi, M.H.N.; Komaguchi, K.; Tsunoji, N.; Esmat, M.; Fukata, N.; Tomita, O.; Abe, R.; Ohtani, B.; Ide, Y. In situ Blue titania via band shape engineering for exceptional solar H
_{2}production in rutile TiO_{2}. Appl. Catal. B**2021**, 297, 120380. [Google Scholar] [CrossRef] - Wang, Q.; O’Hare, D. Recent advances in the synthesis and application of layered double hydroxide (LDH) nanosheets. Chem. Rev.
**2012**, 112, 4124–4155. [Google Scholar] [CrossRef] [PubMed] - Huo, W.; Cao, T.; Liu, X.; Xu, W.; Dong, B.; Zhang, Y.; Dong, F. Anion intercalated layered-double-hydroxide structure for efficient photocatalytic NO remove. Green Energy Environ.
**2019**, 4, 270–277. [Google Scholar] [CrossRef] - Wang, Q.; Tay, H.H.; Ng, D.J.W.; Chen, L.; Liu, Y.; Chang, J.; Zhong, Z.; Luo, J.; Borgna, A. The Effect of Trivalent Cations on the Performance of Mg-M-CO
_{3}Layered Double Hydroxides for High-Temperature CO_{2}Capture. ChemSusChem**2010**, 3, 965–973. [Google Scholar] [CrossRef] - Doustkhah, E.; Hassandoost, R.; Khataee, A.; Luque, R.; Assadi, M.H.N. Hard-templated metal-organic frameworks for advanced applications. Chem. Soc. Rev.
**2021**, 50, 2927–2953. [Google Scholar] [CrossRef] - Mohapatra, L.; Parida, K. A review on the recent progress, challenges and perspective of layered double hydroxides as promising photocatalysts. J. Mater. Chem. A
**2016**, 4, 10744–10766. [Google Scholar] [CrossRef] - Cai, X.; Shen, X.; Ma, L.; Ji, Z.; Xu, C.; Yuan, A. Solvothermal synthesis of NiCo-layered double hydroxide nanosheets decorated on RGO sheets for high performance supercapacitor. Chem. Eng. J.
**2015**, 268, 251–259. [Google Scholar] [CrossRef] - Balcik, C.; Ozbey-Unal, B.; Cifcioglu-Gozuacik, B.; Keyikoglu, R.; Karagunduz, A.; Khataee, A. Fabrication of PSf nanocomposite membranes incorporated with ZnFe layered double hydroxide for separation and antifouling aspects. Sep. Purif. Technol.
**2022**, 285, 120354. [Google Scholar] [CrossRef] - Li, B.; He, J.G.; Evans, D.; Duan, X. Inorganic layered double hydroxides as a drug delivery system-intercalation and in vitro release of fenbufen. Appl. Clay Sci.
**2004**, 27, 199–207. [Google Scholar] [CrossRef] - Bi, X.; Zhang, H.; Dou, L. Layered Double Hydroxide-Based Nanocarriers for Drug Delivery. Pharmaceutics
**2014**, 6, 298–332. [Google Scholar] [CrossRef] [PubMed] - Constantino, V.R.; Pinnavaia, T.J. Basic properties of ${\mathrm{Mg}}_{1-x}^{2+}{\mathrm{Al}}_{x}^{3+}$ layered double hydroxides intercalated by carbonate, hydroxide, chloride, and sulfate anions. Inorg. Chem.
**1995**, 34, 883–892. [Google Scholar] [CrossRef] - Lu, Z.; Zhu, W.; Lei, X.; Williams, G.R.; O’Hare, D.; Chang, Z.; Sun, X.; Duan, X. High pseudocapacitive cobalt carbonate hydroxide films derived from CoAl layered double hydroxides. Nanoscale
**2012**, 4, 3640–3643. [Google Scholar] [CrossRef] [PubMed][Green Version] - Parida, K.; Mohapatra, L. Carbonate intercalated Zn/Fe layered double hydroxide: A novel photocatalyst for the enhanced photo degradation of azo dyes. Chem. Eng. J.
**2012**, 179, 131–139. [Google Scholar] [CrossRef] - Okoronkwo, M.U.; Glasser, F.P. Strätlingite: Compatibility with sulfate and carbonate cement phases. Mater. Struct.
**2016**, 49, 3569–3577. [Google Scholar] [CrossRef][Green Version] - Sasai, R.; Sato, H.; Sugata, M.; Fujimura, T.; Ishihara, S.; Deguchi, K.; Ohki, S.; Tansho, M.; Shimizu, T.; Oita, N.; et al. Why Do Carbonate Anions Have Extremely High Stability in the Interlayer Space of Layered Double Hydroxides? Case Study of Layered Double Hydroxide Consisting of Mg and Al (Mg/Al = 2). Inorg. Chem.
**2019**, 58, 10928–10935. [Google Scholar] [CrossRef] - Goh, K.H.; Lim, T.T.; Dong, Z. Enhanced Arsenic Removal by Hydrothermally Treated Nanocrystalline Mg/Al Layered Double Hydroxide with Nitrate Intercalation. Environ. Sci. Technol.
**2009**, 43, 2537–2543. [Google Scholar] [CrossRef] - Tahawy, R.; Doustkhah, E.; Abdel-Aal, E.S.A.; Esmat, M.; Farghaly, F.E.; El-Hosainy, H.; Tsunoji, N.; El-Hosiny, F.I.; Yamauchi, Y.; Assadi, M.H.N.; et al. Exceptionally stable green rust, a mixed-valent iron-layered double hydroxide, as an efficient solar photocatalyst for H
_{2}production from ammonia borane. Appl. Catal. B**2021**, 286, 119854. [Google Scholar] [CrossRef] - Mishra, G.; Dash, B.; Pandey, S. Layered double hydroxides: A brief review from fundamentals to application as evolving biomaterials. Appl. Clay Sci.
**2018**, 153, 172–186. [Google Scholar] [CrossRef] - Mallakpour, S.; Hatami, M.; Hussain, C.M. Recent innovations in functionalized layered double hydroxides: Fabrication, characterization, and industrial applications. Adv. Colloid Interface Sci.
**2020**, 283, 102216. [Google Scholar] [CrossRef] [PubMed] - Palmer, S.J.; Frost, R.L.; Nguyen, T. Hydrotalcites and their role in coordination of anions in Bayer liquors: Anion binding in layered double hydroxides. Coord. Chem. Rev.
**2009**, 253, 250–267. [Google Scholar] [CrossRef][Green Version] - Bookin, A.; Drits, V. Polytype diversity of the hydrotalcite-like minerals I. Possible polytypes and their diffraction features. Clays Clay Miner.
**1993**, 41, 551–557. [Google Scholar] [CrossRef] - Fan, G.; Li, F.; Evans, D.G.; Duan, X. Catalytic applications of layered double hydroxides: Recent advances and perspectives. Chem. Soc. Rev.
**2014**, 43, 7040–7066. [Google Scholar] [CrossRef] - Dewangan, N.; Hui, W.M.; Jayaprakash, S.; Bawah, A.R.; Poerjoto, A.J.; Jie, T.; Jangam, A.; Hidajat, K.; Kawi, S. Recent progress on layered double hydroxide (LDH) derived metal-based catalysts for CO
_{2}conversion to valuable chemicals. Catal. Today**2020**, 356, 490–513. [Google Scholar] [CrossRef] - Wang, Y.; Yan, D.; El Hankari, S.; Zou, Y.; Wang, S. Recent Progress on Layered Double Hydroxides and Their Derivatives for Electrocatalytic Water Splitting. Adv. Sci.
**2018**, 5, 1800064. [Google Scholar] [CrossRef] - Xu, M.; Wei, M. Layered Double Hydroxide-Based Catalysts: Recent Advances in Preparation, Structure, and Applications. Adv. Funct. Mater.
**2018**, 28, 1802943. [Google Scholar] [CrossRef] - Kohn, W.; Sham, L.J. Self-consistent equations including exchange and correlation effects. Phys. Rev.
**1965**, 140, A1133–A1138. [Google Scholar] [CrossRef][Green Version] - Payne, M.C.; Teter, M.P.; Allan, D.C.; Arias, T.; Joannopoulos, J.D. Iterative minimization techniques for ab initio total-energy calculations - molecular-dynamics and conjugate gradients. Rev. Mod. Phys.
**1992**, 64, 1045–1097. [Google Scholar] [CrossRef][Green Version] - Clark, S.J.; Segall, M.D.; Pickard, C.J.; Hasnip, P.J.; Probert, M.I.J.; Refson, K.; Payne, M.C. First principles methods using CASTEP. Z. Kristallogr. Cryst. Mater.
**2005**, 220, 567–570. [Google Scholar] [CrossRef][Green Version] - Ceperley, D.M.; Alder, B.J. Ground State of the Electron Gas by a Stochastic Method. Phys. Rev. Lett.
**1980**, 45, 566–569. [Google Scholar] [CrossRef][Green Version] - Lejaeghere, K.; Speybroeck, V.V.; Oost, G.V.; Cottenier, S. Error Estimates for Solid-State Density-Functional Theory Predictions: An Overview by Means of the Ground-State Elemental Crystals. Crit. Rev. Solid State Mater. Sci.
**2014**, 39, 1–24. [Google Scholar] [CrossRef][Green Version] - Ortmann, F.; Bechstedt, F.; Schmidt, W.G. Semiempirical van der Waals correction to the density functional description of solids and molecular structures. Phys. Rev. B
**2006**, 72, 205101. [Google Scholar] [CrossRef][Green Version] - McNellis, E.R.; Meyer, J.; Reuter, K. Azobenzene at coinage metal surfaces: Role of dispersive van der Waals interactions. Phys. Rev. B
**2009**, 80, 205414. [Google Scholar] [CrossRef][Green Version] - Pfrommer, B.G.; Cote, M.; Louie, S.G.; Cohen, M.L. Relaxation of crystals with the quasi-Newton method. J. Comput. Phys.
**1997**, 131, 233–240. [Google Scholar] [CrossRef][Green Version] - Pham, A.; Assadi, M.H.N.; Yu, A.B.; Li, S. Critical role of Fock exchange in characterizing dopant geometry and magnetic interaction in magnetic semiconductors. Phys. Rev. B
**2014**, 89, 155110. [Google Scholar] [CrossRef][Green Version] - Cococcioni, M.; de Gironcoli, S. Linear response approach to the calculation of the effective interaction parameters in the LDA+U method. Phys. Rev. B
**2005**, 71, 035105. [Google Scholar] [CrossRef][Green Version] - Loschen, C.; Carrasco, J.; Neyman, K.M.; Illas, F. First-principles LDA + U and GGA + U study of cerium oxides: Dependence on the effective U parameter. Phys. Rev. B
**2007**, 75, 035115. [Google Scholar] [CrossRef][Green Version] - Jain, A.; Ong, S.P.; Hautier, G.; Chen, W.; Richards, W.D.; Dacek, S.; Cholia, S.; Gunter, D.; Skinner, D.; Ceder, G.; et al. The Materials Project: A materials genome approach to accelerating materials innovation. APL Mater.
**2013**, 1, 011002. [Google Scholar] [CrossRef][Green Version] - Stokes, H.T.; Hatch, D.M. FINDSYM: Program for identifying the space-group symmetry of a crystal. J. Appl. Crystallogr.
**2005**, 38, 237–238. [Google Scholar] [CrossRef][Green Version] - Assadi, M.H.N.; Katayama-Yoshida, H. Covalency a Pathway for Achieving High Magnetisation in TMFe
_{2}O_{4}Compounds. J. Phys. Soc. Jpn.**2019**, 88, 044706. [Google Scholar] [CrossRef] - Jaubertie, C.; Holgado, M.; San Román, M.; Rives, V. Structural characterization and delamination of lactate-intercalated Zn, Al-layered double hydroxides. Chem. Mater.
**2006**, 18, 3114–3121. [Google Scholar] [CrossRef]

**Figure 1.**(

**a**) The conventional cell of $TM{\left(OH\right)}_{2}$ layered double hydroxide compounds in hexagonal representation with group $R\overline{3}m$ and space group number 166. (

**b**) The rhombohedral representation of the same structure used for most calculations. In hexagonal representation, ${a}_{h}={b}_{h}$, ${\alpha}_{h}={\beta}_{h}={90}^{\circ}$, and ${\gamma}_{h}={120}^{\circ}$. In the rhombohedral presentation, the lattice parameters ${a}_{r}={b}_{r}={c}_{r}$ and ${\alpha}_{r}={\beta}_{r}={\gamma}_{r}\ne {90}^{\circ}$. The rhombohedral lattice parameters (denoted with subscript r) are related to hexagonal lattice parameters (denoted with subscript h) according to ${\alpha}_{r}=arccos\{(2{c}_{h}^{2}-3{a}_{h}^{2})/(2{c}_{h}^{2}+6{a}_{h}^{2})\}$, and ${a}_{r}=\sqrt{({a}_{h}^{2}/3)+({c}_{h}^{2}/9)}$.

**Figure 2.**A representative of the LDH compounds intercalated with (

**a**) ${\mathrm{H}}_{2}\mathrm{O}$, (

**b**) ${C}_{3}{H}_{5}{O}_{3}$, and (

**c**) $C{O}_{3}$. The optimised structures had higher cantered monoclinic symmetry with group $C121$ (group number 5) for the water intercalated compounds. The rest of the structures were $P1$.

**Figure 3.**Total and partial density of state of the intercalated layered double hydroxide compounds. The upper row of (

**a**–

**c**) corresponds to the Mn-based compounds. The middle row of (

**d**–

**f**) corresponds to the Fe-based compounds. The lower row of (

**g**–

**i**) corresponds to the Co-based compounds. The first, second, and third columns correspond to ${H}_{2}O$, ${C}_{3}{H}_{5}{O}_{3}$, and $C{O}_{3}$ intercalation. The 3d partial density of states of different TM ions is shown in various shades of blue.

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**MDPI and ACS Style**

Mohammadi, S.; Esmailpour, A.; Doustkhah, E.; Assadi, M.H.N. Stability Trends in Mono-Metallic 3d Layered Double Hydroxides. *Nanomaterials* **2022**, *12*, 1339.
https://doi.org/10.3390/nano12081339

**AMA Style**

Mohammadi S, Esmailpour A, Doustkhah E, Assadi MHN. Stability Trends in Mono-Metallic 3d Layered Double Hydroxides. *Nanomaterials*. 2022; 12(8):1339.
https://doi.org/10.3390/nano12081339

**Chicago/Turabian Style**

Mohammadi, Saeedeh, Ayoub Esmailpour, Esmail Doustkhah, and Mohammad Hussein Naseef Assadi. 2022. "Stability Trends in Mono-Metallic 3d Layered Double Hydroxides" *Nanomaterials* 12, no. 8: 1339.
https://doi.org/10.3390/nano12081339