Stability of Pd Islands on Ag(111) and Au(111)
Stability of Pd Islands on Ag(111) and Au(111)
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DOI：
10.1021/acs.jpcc.2c05386
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发表时间：
2022-12
期刊：
影响因子：
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通讯作者：
Buddhika S. A. Gedara;M. Trenary
中科院分区：
文献类型：
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作者：
Buddhika S. A. Gedara;M. Trenary
用扫描隧道显微镜比较了室温(RT)在Ag(111)和Au(111)表面沉积Pd后形成的Pd岛结构随时间和热处理温度的变化。虽然银和金有许多共同的性质，但它们清洁的(111)表面具有明显不同的结构，这导致了在Pd沉积后明显不同的行为。在Ag(111)表面形成大的Pd岛，并被Ag原子覆盖，同时在Ag(111)表面形成空位坑。在Au(111)面上，形成了较小的Pd岛，形成了可比的Pd覆盖层。与Ag(111)相比，Au(111)表面Au原子对Pd的封顶作用要小得多，也没有观察到空位坑。退火至340K时，98%的Pd岛被Ag(111)面上的Ag原子覆盖，而Au(111)面上不到4%的Pd岛被表面Au原子覆盖，但又没有形成空穴。进一步退火到470K时，Pd扩散到Ag(111)和Au(111)的亚表面。这种对比行为归因于Au(111)上的人字形重构，它为Pd原子提供了更高的结合能，而在Ag(111)上没有这样的位置。
Scanning tunneling microscopy was used to compare the evolution with time and annealing temperature of the structure of Pd islands formed after room-temperature (RT) deposition of Pd on Ag(111) and Au(111). Although silver and gold share many properties, their clean (111) surfaces have distinctly different structures, and this leads to distinctly different behavior following Pd deposition. On Ag(111), large Pd islands form and become capped by Ag atoms with the simultaneous formation of vacancy pits on the Ag(111) surface. On Au(111), smaller Pd islands form for comparable Pd coverages. In contrast to Ag(111), much less capping of Pd by Au atoms occurs on the Au(111) surface at RT and no vacancy pits were observed. Upon annealing to 340 K, 98% of the Pd islands were capped by Ag atoms on Ag(111), whereas less than 4% of Pd islands on Au(111) were covered by surface Au atoms, but again without forming vacancy pits. Upon further annealing to 470 K, Pd diffuses into the subsurface of both Ag(111) and Au(111). The contrasting behavior is attributed to the herringbone reconstruction on Au(111), which provides sites with higher binding energies for Pd atoms, whereas such sites are not present on Ag(111).