Gemini surfactant controlled preparation of well-ordered lamellar mesoporous molybdenum oxide

Abstract

A series of well-ordered lamellar mesoporous molybdenum oxides were prepared using gemini surfactant [C n H2n+1N+(CH3)2–(CH2)2–N+(CH3)2C n H2n+1] · 2Br−(denoted as C n-2-n , n = 12, 14 and 16) as the structure-directing agent and ammonium heptamolybdate tetrahydrate (NH4)6Mo7O24 · 4H2O as the precursor. The obtained samples were characterized by X-ray powder diffraction, thermal analysis, transmission electron microscopy and nitrogen adsorption–desorption. Results showed that contrary to complete structure collapse after removing tetradecyltrimethylammonium bromide (TTAB) from molybdenum oxide/TTAB composite, the lamellar mesostructure was retained after removal of C n-2-n from corresponding composite. The effects of alkyl chain length and concentration of gemini surfactants on the structure of the mesoporous molybdenum oxide were also investigated. The specific surface area of extracted sample was as high as 116 m2 g−1. The maintenance of the lamellar mesostruture was due to the strong self-assembly ability of gemini surfactants and the strong electrical interaction between gemini surfactants and molybdenum oxide.