Manipulating active sites on carbon nanotube materials for highly efficient hydrogen storage

Abstract

The active sites in porous carbon nanotube (CNT) would determine hydrogen storage performance of CNT. Here, we reported an effective, simple and controllable strategy to improve the hydrogen storage property of function group grafted CNT (fg-CNT). N-CNT-M (La2O3, Ni) would be obtained by the mixture of fg-N-CNT and metallic precursor at calcination of 600 °C. N-CNT-La2O3 has the highest H2 storage capacity of 7.4 wt%, displaying stable hydrogen adsorption/ desorption cycles for more than 20 times at 100 °C and 18 bar. fg-Ni-CNT-PLLA were formed by electrostatic interactions between CN bond of amide and carbonyl of l-polylactic acid (PLLA). fg- Ni-CNT-PLLA also has H2 storage capacity of 6.2 wt% at 100 °C and 18 bar. The experiment found that metal ions or PLLA might be dispersed uniformly in CNT by adjusting the ratio of grafted hydroxyl (OH) to acylamino (–CONH2). N-CNT-La2O3 has better hydrogen storage performance than fg-CNT-PLLA because the aggregation of CNT would be caused by the molecular movement of PLLA during hydrogenation and dehydrogenation. This work provides guidance for the development of efficient hydrogen storage materials.