TiO 2 nanotubes can reproducibly store up to∼2 wt% H 2 at room temperature and 6 MPa. However, only about 75% of this stored hydrogen can be released when the hydrogen pressure is lowered to ambient conditions, suggesting that both physisorption and chemisorption are responsible for the hydrogen uptake. FTIR spectroscopy, temperature-programmed desorption (TPD), and pressure-composition (P-C) isotherms suggest that 75% of the H 2 is physisorbed and can be reversibly released upon pressure reduction. Approximately 13% is weakly chemisorbed and can be released at 70°C as H 2, and ∼ 12% is bonded to oxide ions and released only at temperatures above 120°C as H 2O.
|Number of pages||3|
|State||Published - 13 Jun 2005|