Nirun Ruankaew

The first-principles approach is a useful tool for developing 2D/2D heterojunction catalysts for electro- and photo-catalytic nitrogen reduction reactions.

In this study, we investigated the intercalation of water and K⁺ to interlayer of Montmorillonite (MMT) nanoclay by using the statistical mechanics theory of molecular liquids or three-dimensional reference interaction site model (3D-RISM). The results from 3D-RISM show that the distribution of water and K⁺ bound to the MMT’s surfaces with different sites. Moreover, the results from 3D-RISM show the amount of water corresponds to the d-basal spacing of the clay, which are in good agreements with other simulation methods as well as experimental.

Ferric hexacyanoferrate (FeHCF) or Prussian blue (PB) exhibits selective alkali ion adsorption and has great potential for use in various applications. In the present work, alkali ion (Li⁺, Na⁺, K⁺, and Cs⁺) and water configurations in defective PB (d-PB) were studied by using the statistical mechanics of molecular liquids. The three-dimensional (3D) distribution functions of the ions and water were determined by solving the 3D-reference interaction site model (RISM) equation of systems of a unit lattice of d-PB in electrolyte solutions, i.e., LiCl, NaCl, KCl, and CsCl. The results show the difference in the ion–water configurations and distributions between small (Li⁺ and Na⁺) and large ions (K⁺ and Cs⁺). The adsorption sites of Li⁺ and Na⁺ are located off-center and lie on the diagonal axis. By contrast, the larger ions, K⁺ and Cs⁺, are adsorbed at the center of the unit cell. The degree of dehydration due to the adsorption of alkali ions indicates that there was no water exchange during Li⁺ and Na⁺ adsorption, whereas two and three water molecules were removed after adsorption of K⁺ or Cs⁺ in the unit cell.

Prussian Blue (PB) or ferric hexacyanoferrate (II) is one of the most attractive materials in green battery industry. It has defective structure (d-PB), Fe 4 III [ Fe II ( CN ) 6 ] 3 ⋅ xH 2 O ( x ≈ 14 − 16 ) , that one of [Fe(CN)₆]⁴⁻ group is missing, and hydrated with water molecules at the 24e empty nitrogen site. In this study, we investigated the distributions of water and Li⁺ in d-PB by using three-dimensional reference interaction site-model (3D-RISM) theory, which is a statistical mechanics theory of molecular liquids. The theory can examine the selective ion adsorption in solvated molecular materials. The results from 3D-RISM show that there are 14 water molecules located in different positions inside the d-PB lattice, which are in good agreement with experiment. Moreover, we also found the Li⁺ distributed at inside d-PB lattice positioned closely to the 32f spherical cavity of d-PB.