A simplified synthesis of N-doped zeolite-templated carbons, the control of the level of zeolite-like ordering and its effect on hydrogen storage properties

Nitrogen-doped, microporous carbon materials have been prepared using zeolite EMC-2 as a hard template and acetonitrile as the carbon source via chemical vapour deposition (CVD) in the temperature range 700–950 °C. The carbon products exhibited high surface areas (up to 3360 m2/g), high pore volumes (up to 1.71 cm3/g) and had zeolite-like structural ordering derived from the template. The carbons had XRD patterns that exhibited two well resolved peaks and TEM images that showed well ordered pore channels. A high proportion of porosity (up to 85% of surface area and 73% of pore volume) for the best ordered carbon arose from micropores that exhibited narrow size distribution in the range 5–15 Å. The carbons generally retained the morphology of the template with solid-core particles at CVD temperatures up to 900 °C and hollow shells at 950 °C. The carbons had total hydrogen storage capacities up to 6.0 wt.% at −196 °C and 20 bar. The hydrogen uptake was found to be dependent on the level of zeolite-like ordering and the resulting textural properties. Particularly, high levels of zeolite-like ordering favoured micropores of size <15 Å which are favourable for higher hydrogen uptake capacities.

Graphical abstractNitrogen-doped, microporous carbons were prepared by CVD using acetonitrile and zeolite EMC-2 (as a template). The carbon products had high surface areas (3360 m2/g), pore volumes (1.71 cm3/g), narrow pore size distribution (5–15 Å), resulting in hydrogen storage capacities up to 6.0 wt.% (at −196 °C and 20 bar).Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► N-doped nanoporous carbons formed by CVD of acetonitrile. ► Zeolite template used for controlled microporosity. ► High surface area carbons formed >3000 m2/g. ► High hydrogen storage capacities 6 wt.%.