Condensation of borazinic precursors for mesoporous boron nitride synthesis by carbon nanocasting
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The influence of different borazinic precursors on mesoporous boron nitride synthesis by using a nanocasting process of a mesoporous CMK-3 carbon is presented. Two borazinic precursors, the tri(methylamino)borazine (MAB) and the tri(chloro)borazine (TCB), have been converted to boron nitride (BN) inside the mesopores of a CMK-3 carbon mesoporous template by using thermal or chemical polycondensation processes. Ordered mesoporous boron nitride with a specific surface area around 800 m2/g, a mesoporous volume around 0.6 cm3/g, and a pore-size distribution located at 6 nm in diameter was synthesized by thermal condensation of a molecular MAB precursor. In addition, chemical condensation of TCB led to a disordered mesoporous boron nitride.
I. INTRODUCTION
Boron nitride is a promising material capable of withstanding high temperatures and corrosive environments.1,2 Ordered mesoporous materials, first introduced in 1992,3 have potential applications in catalysis, adsorption, and nanochemistry.4–8 Ordered mesoporous boron nitride could then be very useful in applications of porous materials involving high temperatures or in corrosive media, such as catalyst supports, chromatography, or separation materials. Moreover boron nitride nanotubes have been found to be promising materials for hydrogen storage applications and could be prepared by templating strategy.9,10 The hard-template process consists in the replication of nanoscale structures by direct templating process, as in the case of mesoporous carbon, recently developed CMK-i, using mesoporous silica as templates.11,12 In the case of the CMK-3 synthesis, the simplest method involves carbonizing sucrose or phenolic resin inside the pores of the mesoporous silica SBA-1513 and by removing the silica template by washing with hydrofluoric acid or sodium hydroxyde solutions. Different mesoporous silica templates have been used to synthesize ordered mesoporous carbon with cubic (Ia3d and Pm3n) or hexagonal (p6mm) symmetries.14–18 CMK-3 nanocasting has been used for the regeneration of mesoporous silica SBA-1519–21 and also for synthesis of a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2007.0028 26
http://journals.cambridge.org
J. Mater. Res., Vol. 22, No. 1, Jan 2007 Downloaded: 04 Dec 2014
mesoporous oxides22,23 or aluminosilicate molecular sieves.24 Nonordered porous boron nitride with high specific surface area has already been synthesized and used for catalytic applications.25–28 The synthesis of ordered mesoporous boron nitride has been evidenced for the first time, following a mesoporous carbon nanocasting procedure using a tri(methylamino)borazine precursor (MAB) as boron nitride source.29 A comparison between silica and carbon templating processes with tri(methylamino)borazine shows that the silica template is not efficient in preparing an ordered mesoporous boron nitride.30 Another group has recently reported the successful synthesis of mesoporous boron nitride via a carbon templating using boron trioxide as a
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