Alloying effects on hydrogen permeability of V without catalytic Pd overlayer

Highlights: • Air–treated V–based alloy membranes without catalytic Pd overlayer are found to possess excellent hydrogen permeability. • They also exhibit good durability at high temperature. • Alloying effects are discussed in view of the new description of hydrogen permeation based on hydrogen chemical potential. - Abstract: Hydrogen permeability of air–treated V–based alloy membranes without Pd coating have been investigated. The diffusion–limiting hydrogen permeation reaction takes place even without catalytic Pd overlayer on the surface. It is shown that pure V and its alloy membranes without Pd overlayer possess excellent hydrogen permeability and good durability at high temperature. The new description of hydrogen permeation based on hydrogen chemical potential has been applied and the hydrogen flux is analyzed in terms of the mobility of hydrogen atom and the PCT factor, f_PCT