The Fabrication And Characterization Of Mesoporous Metal And Bimettalic Films By Lyotropic Liquid Crystalline Templating Strategy

Owing to their unique structures and capabilities, ordered mesoporous materials attract extensive researches in different areas and possess various potential applications in separation and purification, biomaterials, chemical industry, catalysis, information communication, environment, energy and new pattern assembled materials(or as nanoreactors fabricating new type of nanomaterials with special light, electricity, magnetism performances ). Lyotropic liquid crystal templating method is one of the vital techniques in fabricating mesoporous materials. At present the main approaches for synthesizing nanostructured metallic films is electrodeposition.Mesoporous Platinum films, Nickel films and Platinum-Nickel films were fabricated in this paper using lyotropic liquid crystal as templates which were formed by non-ionic surfactant Brij56. The ordered nanostructures of lyotropic liquid crystal templates and products were characterized by XRD. TEM,SEM were utilized to observe the morphology of the products.Hexagonal lyotropic liquid crystals were prepared by mixing Brij56 and aqueous HCPA solutions with different concentrations. XRD analysis indicated that the concentration of H2PtCl6 solutions in aqueous domain had no impact on the structures and lattice parameters of hexagonal lyotropic liquid crystals.Reduction of metallic ions dissolved in aqueous domains of hexagonal liquid crystals by hydrazine dydrate produced nanostructured metallic films deposited onα-Al₂O₃ substrates. The as-resulted films possess the same nanostructure as that of hexagonal lyotropic liquid crystals. The effect of the concentration of H2PtCl6 solutions on the nanostructure of the products was studied. The corresponding relationship between templates and the templated products is discussed. The reasons for the mismatch between products and templates were preliminarily analysed. Lamellar lyotropic liquid crystal was prepared by mixing NiCl2 solution and Brij56. Nanostructured metallic Ni films which were deposited on the surface ofα-Al₂O₃ substrates were fabricated by chemical deposition. The effect of reducing agent on the ordering of the products was studied.Pt-Ni bimettalic films were fabricated on the surface ofα-Al₂O₃ substrates by the reaction between reducing agent KBH4 and H2PtCl6 and NiCl2 dissolved in the aqueous domain of hexagonal lyotropic liquid crystal.Deposited on porous substrates, ordered nanostructured metallic/bimetallic films with well-regulated nanostructure and higher specific surface areas may have potential wide applications in membrane reactors.