DFT study on MgAl-layered double hydroxides with different interlayer anions: structure, anion exchange, host-guest...

Area of Science:

• Materials Science
• Computational Chemistry
• Nanotechnology

Background:

• Layered double hydroxides (LDHs) are versatile host-guest materials.
• Guest anions are crucial for tailoring LDH properties and functionalities.

Purpose of the Study:

• To investigate the impact of various anions on the structural and electronic properties of MgAl-LDHs.
• To establish structure-property relationships for anion-controlled LDH materials.

Main Methods:

• Density functional theory (DFT) calculations were employed.
• Mg_nAl-LDHs with varying Mg/Al ratios (n = 1.6 to 8.0) and nine different anions were studied.

Main Results:

• Interlayer distances correlate with anion inclination, size, charge, and water content.
• Anion charge dictates binding energy, revealing a specific anion exchange sequence: PO₄^3- > CO₃^2- > SO₄^2- > OH^- > F^- > Cl^- > Br^- > NO₃^- > I^-.
• Interlayer anions, not hydroxyl groups, form the basic sites of MgAl-LDHs, with higher anion charge enhancing basicity.

Conclusions:

• DFT calculations provide insights into anion-LDH interactions.
• Findings support the design of functional LDHs by controlling interlayer anions.
• This research offers theoretical guidance for developing anion-controlled LDH materials.