Lan Yuejing, Tang Ru, Ye Rongxing, Su Minan, Lei Qianghua, Li Fei, Tian Xiaofeng, Song Jiangfeng, Zhou Linsen
College of Nuclear Technology and Automation Engineering, Chengdu University of Technology, Chengdu, 610059, China.
Institute of Materials, China Academy of Engineering Physics, Mianyang, 621907, China.
Phys Chem Chem Phys. 2024 Mar 20;26(12):9617-9627. doi: 10.1039/d3cp06251a.
Theoretical calculations are performed to elucidate the adsorption behaviors and poisoning effects of CO gas on the ZrCo surface, which drastically limits its application in hydrogen isotopic storage. Specifically, the ionic Zr-Co bond on the surface leads to unique CO adsorption structures on different sites. The CO molecule tends to prefer a tilted adsorption configuration on the Co-Co bridge site. The electronic structures, charge distributions, and bonding characteristics are further explored to study the CO adsorption properties, which obey the electron density donation and back-donation mechanism. For different CO coverages, the stepwise adsorption energies of CO increase with the increasing of coverage, reaching the saturated coverage at = 11. Then, the effects of temperature and partial pressure on CO coverage are evaluated using atomic thermodynamics. The computed phase diagram shows that the ZrCo(110) surface has a stable coverage of = 6 at ambient temperature under ultrahigh vacuum conditions. The pre-adsorbed CO molecules lead to the charge redistribution and the d-band center downshift on the surface, which significantly affect hydrogen adsorption and dissociation. Our results provide insights into the poisoning mechanisms of the impurity gas on ZrCo alloys, which can be beneficial for designing high-performance ZrCo-based alloys with improved poisoning tolerance.
进行理论计算以阐明CO气体在ZrCo表面的吸附行为和中毒效应，这极大地限制了其在氢同位素存储中的应用。具体而言，表面上的离子Zr-Co键导致不同位点上独特的CO吸附结构。CO分子倾向于在Co-Co桥位上采取倾斜吸附构型。进一步探索电子结构、电荷分布和键合特性以研究CO吸附特性，其遵循电子密度给予和反馈给予机制。对于不同的CO覆盖度，CO的逐步吸附能随着覆盖度的增加而增加，在θ = 11时达到饱和覆盖度。然后，利用原子热力学评估温度和分压对CO覆盖度的影响。计算得到的相图表明，在超高真空条件下，ZrCo(110)表面在室温下具有稳定的θ = 6覆盖度。预先吸附的CO分子导致表面电荷重新分布和d带中心下移，这显著影响氢的吸附和解离。我们的结果为杂质气体对ZrCo合金的中毒机制提供了见解，这有助于设计具有更高抗中毒能力的高性能ZrCo基合金。
