氧化气氛中PdAg纳米合金的表面相稳定性与原子电荷的关系
Surface Phase Stability of PdAg Nanoalloys and Its Relevance to Atomic Charge in Oxidizing Atmospheres
卞维琦 1梁雪松1
作者信息
- 1. 中国船舶集团有限公司第七二三研究所,江苏 扬州 225009
- 折叠
摘要
在多相催化中,纳米合金的氧化和偏析可能导致特殊的电催化性质.基于第一性原理原子热力学方法,本文通过表面相稳定性图计算氧化气氛中Pd6@Ag32和Ag6@Pd32核壳纳米合金的早期氧化阶段.Ag38纳米团簇(ΔμO=-0.95 eV)的稳定性高于Pd38纳米团簇(ΔμO=-1.3 eV),但是Pd6@Ag32核壳纳米合金(ΔμO=-0.9 eV)显示出高于Ag38纳米团簇的表面相稳定性,而Pd偏析的Pd6@Ag32纳米合金的稳定性低于Ag38纳米团簇.同时,Ag6@Pd32核壳纳米合金(ΔμO=-1.5 eV)的表面相稳定性比Pd38纳米团簇低,而Ag偏析的Ag6@Pd32纳米合金显示出高于Pd38纳米团簇的表面相稳定性.表面Ag原子偏析越多的Pd6@Ag32和Ag6@Pd32核壳纳米合金具有更高的表面相稳定性.表面相稳定性的顺序遵循原子电荷的趋势,即越多的负电荷对应于越低的表面相稳定性.研究结果能够为设计燃料电池中具有合适表面相稳定性的PdAg基纳米合金催化剂提供有效信息.
Abstract
The oxidation and segregation of nanoalloys can lead to unique electrocatalytic performance in heteroge-neous catalysis.The early stage of oxidation on Pd6@Ag32 and Ag6@Pd32 core-shell nanoalloys was calculated by the sur-face phase stability diagrams using a first-principles atomistic thermodynamics method in oxidizing atmospheres.Ag38 nanoparticle with ΔμO=-0.95 eV is more stable than Pd38 nanoparticle with ΔμO=-1.3 eV.Unexpectedly,Pd6@Ag32 core-shell nanoalloy with ΔμO=-0.9 eV exhibits better surface phase stability than Ag38 nanoparticle but Pd-segregat-ed Pd6@Ag32 nanoalloys have lower stability than Ag38 nanoparticle,and Ag6@Pd32 core-shell nanoalloy with ΔμO=-1.5 eV displays lower surface phase stability than Pd38 nanoparticle but Ag-segregated Ag6@Pd32 nanoalloys show bet-ter surface phase stability than Pd38 nanoparticle.Surface-segregated Pd6@Ag32 and Ag6@Pd32 core-shell nanoalloys with more surface Ag atoms tend to possess the higher surface phase stability.The order of surface phase stability fol-lows the same trend of atomic charges,that is,the more negative charges corresponding to the lower surface phase sta-bility.The results can provide useful information for designing PdAg-based catalyst materials with appropriate surface phase stability towards fuel cells.
关键词
纳米合金/密度泛函理论/表面偏析/表面相稳定性/原子电荷Key words
nanoalloy/density functional theory/surface segregation/surface phase stability/atomic charge引用本文复制引用
出版年
2024
NETL
NSTL
万方数据