Halloysite nanotubes as hydrogen storage materials

The hydrogen adsorption capacities of halloysite nanotubes (HNTs), subjected to different treatments, were investigated at room temperature. The three different treatments included thermal, acid, and palladium modification. The hydrogen adsorption capacity of the HNTs was 0.436 % at 2.63 MPa and 298 K whereas those of the thermally treated HNTs, palladium-modified HNTs (Pd-HNTs), and acid-treated HNTs (A-HNTs), under the same conditions, were 0.263, 1.143, and 1.371 %, respectively. The hydrogen adsorption capacities of both HNTs and treated HNTs are among the highest values reported in the literature so far. Large surface areas were advantageous in promoting hydrogen adsorption via a physisorption mechanism, which was directly related to the aluminosilicate structure of HNTs. It was also possible to enhance the hydrogen adsorption capacity through a chemisorption or spillover mechanism by modifying HNTs with Pd. The HNTs and treated HNTs show potential as physisorption-based mediums for hydrogen storage at room temperature, in particular HNTs and A-HNTs show excellent stability and high hydrogen adsorption capacities.