Exploring the role of Nb/Pd doping on the resistance to oxygen poisoning on the ZrCo(110) surface: A first-principles study

In practice, zirconium–cobalt (ZrCo) alloys are usually poisoned by various impurity gases, resulting in severe loss of hydrogen storage performance. This study is dedicated to revealing the influence of Nb/Pd doping on oxygen poisoning resistance of ZrCo-based system on the basis of the density functional theory. Adsorption energies are employed to evaluate the adsorption performance of oxygen molecule on the ZrCo(110) surface, demonstrating that the Nb/Pd doping leads to a degraded adsorption capability. It was also discovered that the dopants are unfavorable for the oxygen atom adsorption at the hollow sites. The crystal orbital Hamilton population analysis further confirms that the doping weakens the chemical bonding between oxygen atom and adjacent atoms. In addition, the diffusion barrier for oxygen atom is determined by the climbing image nudged elastic band method. The results show that there is a higher diffusion barrier for the Pd doping for the surface migration and subsurface penetration, thereby enhancing the resistance of the alloy to oxygen poisoning. As compared, the Nb doping exhibits an opposite trend for diffusion behavior. This work is expected to offer valuable insights into the mechanism of oxygen poisoning on the ZrCo(110) surface after element doping, beneficial to the development of hydrogen storage materials for practical applications.