Effect of Helium-, Iron-, and Platinum- Ion Implantation on the Permeation of Hydrogen through Iron Membranes.

摘要

A preliminary study was made of the effect of various ions implanted in iron on the absorption of hydrogen by Ferrovac-E iron. Using the permeation technique, it was found that the location of implanted Pt, as modified by selective dissolution of iron from the surface, affects the kinetics of the hydrogen evolution reaction and, hence, of the hydrogen absorption process. The rate of hydrogen absorption decreased with increase in Pt concentration on the surface in both 0.1N NaOH and 0.1N H2SO4. A catalytic mechanism is proposed to explain the marked reduction in hydrogen permeation. There are no significant differences in the permeation behavior of unimplanted and helium- or iron-implanted iron membranes in 0.1N NaOH. The experimentally observed Tafel slope, the permeation-charging potential relationship, and the permeation-charging current relationship indicate a coupled discharge-recombination mechanism of hydrogen evolution on He-, Fe- or Pt-implanted iron. At higher cathodic overpotentials in 0.1N NaOH, corresponding to potentials more negative than -1.0V (SHE), another mechanism of hydrogen evolution is indicated. Selective dissolution of iron from the Pt-implanted Fe surface layer is indicated by Rutherford backscattering analyses to involve diffusion of Pt into the iron ahead of the receding surface. (Author)