Nitrogen modified templated carbons for energy application: Effect of templates and nitrogen precursors

Nitrogen modified templated carbons were prepared by carbonization at 923 K with dwelling time of 3 h. The effects of nitrogen precursors and templates on the surface area, pore structure and nitrogen loading of modified carbons were studied. Acetonitrile and aniline were used as nitrogen precursors, while zeolite and silica gel as inorganic templates. The surface areas of nitrogen modified carbons were reduced as compared to that of unmodified carbons. The effect is more significant for aniline precursor and zeolite template. Irrespective of nitrogen precursors, zeolite and silica gel templates resulted in mainly microporous and mesoporous carbons respectively. The nitrogen modified templated carbons were tested for hydrogen uptake. The hydrogen uptake of silica gel templated carbons increased on incorporation of nitrogen in spite of decrease in surface area. The high uptake of silica gel templated modified carbon can be attributed to higher activation of hydrogen by nitrogen centers present in the carbon network. However, drop in hydrogen uptake for zeolite templated modified carbons may be attributed to significant decrease in surface area. The hydrogen desorption kinetics was observed to depend on porous structure. Presence of micropores offered higher diffusion resistance, making desorption of hydrogen slower.