Carbon hybridized halloysite nanotubes for high-performance hydrogen storage capacities

Abstract

Hybrid nanotubes of carbon and halloysite nanotubes (HNTs) with different carbon:HNTs ratio were hydrothermally synthesized from natural halloysite and sucrose. The samples display uniformly cylindrical hollow tubular structure with different morphologies. These hybrid nanotubes were concluded to be promising medium for physisorption-based hydrogen storage. The hydrogen adsorption capacity of pristine HNTs was 0.35% at 2.65MPa and 298K, while that of carbon coated HNTs with the pre-set carbon:HNTs ratio of 3:1 ( 3 C-HNTs) was 0.48% under the same condition. This carbon coated method could offer a new pattern for increasing the hydrogen adsorption capacity. It was also possible to enhance the hydrogen adsorption capacity through the spillover mechanism by incorporating palladium (Pd) in the samples of HNTs (Pd-HNTs) and 3 C-HNTs (Pd -3 C-HNTs and 3 C-Pd-HNTs are the samples with different location of Pd nanoparticles). The hydrogen adsorption capacity of the Pd-HNTs was 0.50% at 2.65MPa and 298K, while those of Pd -3 C-HNTs and 3 C-Pd-HNTs were 0.58% and 0.63%, respectively. In particular, for this spillover mechanism of Pd-carbon-HNTs ternary system, the bidirectional transmission of atomic and molecular hydrogen ( 3 C-Pd-HNTs) was concluded to be more effective than the unidirectional transmission (Pd -3 C-HNTs) in this work for the first time.