Mesoporous boron nitride and boron-nitride-carbon materials from mesoporous silica templates

We report the synthesis of mesoporous boron nitride materials (boron nitride and a boron-nitride-carbon), via a nitridation/chemical vapour deposition (CVD) route, using mesoporous pure silica SBA-15 or Fe-SBA-15 as hard template, with BH3·NH3, ammonia and acetonitrile as boron, nitrogen and carbon sources respectively. Fe-SBA-15 is obtained by impregnation of Fe(NO3)3·9H2O in SBA-15. The boron precursor, BH3·NH3, is converted into boron nitride within the pores of SBA-15 during nitridation with ammonia at 1150 °C. The boron-nitride-carbon material is obtained by first incorporating carbon (viaCVD at 900 °C using acetonitrile as a carbon source) into the SBA-15/BH3·NH3 composite, followed by nitridation at 1150 °C. The obtained boron nitride materials are porous with relatively high surface areas of 204–380 m2 g–1 and pore volumes in the range 0.46–0.89 cm3 g–1. The boron nitride materials exhibit considerable levels of graphitisation despite the low synthesis temperatures. The use of Fe-SBA-15 as template results in better graphitised boron nitride compared to pure silica SBA-15. The boron-nitride-carbon material exhibits the best graphitisation, and higher surface area and pore volume compared to boron nitride samples. The successful utilization of mesoporous silica, rather than carbon, as a hard template is attractive as it reduces the number of steps in the preparation of the mesoporous boron nitride materials