Rapid direct growth of Li–Al layered double hydroxide (LDH) film on glass, silicon wafer and carbon cloth and characterization of LDH film on substrates

Abstract

This work presents a novel method for directly growing highly oriented Li–Al LDH films on substrates such as glass, Si wafer and carbon cloth in an aqueous alkaline Al³⁺- and Li⁺-containing solution. The substrate samples were each hanged and then respectively immersed in the solutions at 5–35 °C for 20 min or less than 6 h to form the LDH films. The Li–Al LDH film comprised of extra-high-density Li–Al LDH platelets, each standing almost perpendicularly on the surface of the substrate. The LDH film that was fabricated at 5 °C (∼1.4 μm thick) exhibits good UV shielding (with only 9.7% UV transparency) and a maximum of 56% transparency to visible light. A more rapid method (only 20 min needed) can be utilized to develop a Li–Al LDH film to cover both hydrophobic and hydrophilic carbon cloth surfaces. Despite the modification of these surfaces, the Li–Al LDH film on carbon cloths retained or enhanced their original surface properties (including hydrophobicity or hydrophilicity). The LDH film thickness increased with immersion time and/or solution temperature. The thickness reached a plateau during LDH formation. CO₂ in the atmosphere dissolved in the alkaline Al³⁺- and Li⁺-containing solution, yielding CO₃²⁻ ions for Li–Al LDH formation. The heterogeneous nucleation and growth of each LDH platelet on the substrate surface finally produced an LDH film.