Layered double hydroxides as templates for nanocasting porous N-doped graphitic carbons via chemical vapour deposition

Porous carbon materials have been prepared using Mg-Al (Mg/Al = 2) layered double hydroxides (LDH) as template via chemical vapour deposition (CVD) at 600-800 degrees C, with acetonitrile as carbon precursor. Depending on the CVD temperature, the carbons exhibit microporosity, mesoporosity and significant levels of graphitisation. The layer structural ordering of the LDH is somewhat retained in the LDH/carbon composite obtained after CVD, but is lost after removal of the template to generate carbon. Both the LDH/carbon composites and carbons exhibit significant porosity. The composites have a surface area of up to 140 m(2) g(-1), while the surface area of carbons ranges between 200 and 1300 m(2) g(-1). Carbons obtained at CVD temperature of 700-800 degrees C have high surface area (800-1268 m(2) g(-1)) and high pore volume (1.2-1.5 cm(3) g(-1)). The morphology of the LDH template is retained in the carbon materials, which in general consist of an assembly of small flaky particles. The use of acetonitrile as carbon precursor generates N-doped carbon materials with a uniformly incorporated nitrogen content of 7-9 wt%. The carbon materials exhibit significant hydrogen uptake; we obtained a hydrogen uptake capacity, at 20 bar and -196 degrees C, of up to 2.8 wt%. The hydrogen uptake capacity depends on the surface area of the carbons and is therefore influenced by the choice of CVD temperature. (c) 2007 Elsevier Inc. All rights reserved.