(1. 桂林电子科技大学 材料科学与工程学院，桂林 541004；
2. 贺州学院 材料与化学工程学院，贺州 542899；
3. 华南理工大学 材料科学与工程学院，广州 510640；
4. 中南大学 粉末冶金研究院，长沙 410083)
摘 要: BCC结构的V基固溶体有良好的氢渗透性能，在氢分离膜中具有应用潜力。采用第一性原理方法研究Pd掺杂V(100)表面的H吸附和渗透机理，讨论氢覆盖对氢吸附和扩散的影响。计算结果表明：Pd优先取代V(100)表面的第一层V原子。在V-Pd(100)表面不同位置吸附H原子的稳定性由大到小依次为洞位、桥位、顶位，Pd掺杂降低了表面H原子的吸附能力，有利于H原子的解离和缔合效率。Pd掺杂的V(100)表面，H原子从表面扩散到次表面的扩散能垒降低，提高了氢渗透率。随着H原子覆盖度的增加，H吸附于V(100)表面的能力减弱，而吸附于V-Pd(100)表面的能力增强。差分电荷密度的计算结果表明，Pd—H键比V—H键弱，故Pd元素的掺杂能够改善H的渗透性能和解氢能力。
关键字: V基固溶体；Pd掺杂；表面；氢渗透性；第一性原理计算
（1. School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin 541004, China;
2. College of Materials and Chemical Engineering, Hezhou University, Hezhou 542899, China;
3. School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, China;
4. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China）
Abstract:The V-based solid solution with BCC structure has good hydrogen permeability and potential application in hydrogen separation membranes. The first-principles method was used to systematically research the hydrogen adsorption and permeation mechanism on the Pd-doped V(100) surface, and the influence of hydrogen coverage on hydrogen adsorption and diffusion was discussed. The calculation results show that Pd preferentially replaces V atom in the first layer on V(100) surface. The stability of adsorbed H atoms at different positions on the surface of V-Pd(100) is as follows: hole position＞bridge position＞top position. Pd doping reduces the adsorption capacity of surface hydrogen atoms, which is conducive to the dissociation and association efficiency of hydrogen atoms. On the Pd-doped V(100) surface, the diffusion energy barrier of hydrogen atoms from the surface to the subsurface is reduced, which improves the hydrogen permeability. With the coverage of hydrogen atoms increasing, the ability of hydrogen to adsorb on the surface of V(100) decreases, while the ability to adsorb on the surface of V-Pd(100) increases. The calculation results of the differential charge density show that the Pd—H bond is weaker than the V—H bond, so Pd doping can improve the hydrogen permeability and hydrogen desorption ability.
Key words: V-based solid solution; Pd doping; surface; hydrogen permeability; first-principles calculation
