Acta Phys. -Chim. Sin. ›› 2002, Vol. 18 ›› Issue (08): 692-698.doi: 10.3866/PKU.WHXB20020805

• ARTICLE • Previous Articles     Next Articles

Characteristics of Adsorption and Desorption of Hydrogen on Multi-walled Carbon Nanotubes

Zhou Zhen-Hua;Wu Xiao-Man;Wang Yi;Lin Guo-Dong;Zhang Hong-Bin   

  1. College of Chemistry and Chemical Engineering, State Key Laboratory of Physical Chemistry for the Solid Surfaces, Xiamen University, Xiamen 361005
  • Received:2001-12-19 Revised:2002-02-28 Published:2002-08-15
  • Contact: Zhang Hong-Bin

Abstract: Storage capacities of H2 in a kind of multi-walled carbon nanotubes (MWCNTs) and its corresponding system modified with K+ salt were measured using volumetric method, and characteristics of adsorption and desorption of hydrogen on MWCNTs were studied by means of temperature-programmed desorption (TPD) method. The results showed that the storage capacities of H2 in the purified MWCNTs could reach 1.51% (mass fraction) under condition of room temperature and 9.0 MPa, with adsorption of ~99% of the H2 being reversible. A comparative study indicated that the modification of the K+ salt to the MWCNTs did not improve its storage capacity of hydrogen, but led to elevating of desorption temperature of adsorbed hydrogen H2(a) to a certain extent; in addition, the K+ modification resulted also in changing of surface property of the MWCNTs from original hydrophobicity to hydrophilicity. The products desorbed on H2/MWCNTs involved exclusively H2 at T≤ 723 K, and main part of H2 and small amount of CH4,C2H4,and C2H2 at T ≥ 773 K; whereas on H2/K+-MWCNTs,H2O was also involved in the desorbed products, in addition to H2 and small amount of C1/C2-hydrocarbons.The adsorption of H2 on the MWCNTs-based materials is in the two models: associative (molecular state) and dissociative (atomic state).

Key words: Multi-walled carbon nanotubes, MWCNTs-based H2-storage material, Adsorption-desorption characteristics of H2, H2-TPD