Hydrogen absorption-desorption behaviors on oxygen evaluated by electrical resistance measurements

To understand the hydrogen absorption and desorption behaviors of Pd under air, we performed real time measurements of the electrical resistance of Pd under gas mixture with various oxygen contents. The Hydrogen absorption rate was independent of oxygen concentration. Conversely, the hydrogen desorption rate in the presence of oxygen was faster than that without oxygen, suggesting that the additional desorption path including water formation reaction appears in the hydrogen desorption process in the presence of oxygen. The hydrogen concentration in Pd at equilibrium decreased with increasing oxygen concentration in gas phase because the hydrogen absorption sites become partially occupied by oxygen atoms