Spurgeon Peter M, Liu Da-Jiang, Windus Theresa L, Evans James W, Thiel Patricia A
Department of Chemistry, Iowa State University, Ames, Iowa, 50011, USA.
Ames Laboratory - USDOE, Ames, Iowa, 50011, USA.
Chemphyschem. 2021 Feb 16;22(4):349-358. doi: 10.1002/cphc.202000884. Epub 2021 Jan 15.
Chemisorbed species can enhance the fluxional dynamics of nanostructured metal surfaces which has implications for applications such as catalysis. Scanning tunneling microscopy studies at room temperature reveal that the presence of adsorbed sulfur (S) greatly enhances the decay rate of 2D Au islands in the vicinity of extended step edges on Au(111). This enhancement is already significant at S coverages, θ , of a few hundredths of a monolayer (ML), and is most pronounced for 0.1-0.3 ML where the decay rate is increased by a factor of around 30. For θ close to saturation at about 0.6 ML, sulfur induces pitting and reconstruction of the entire surface, and Au islands are stabilized. Enhanced coarsening at lower θ is attributed to the formation and diffusion across terraces of Au-S complexes, particularly AuS and Au S , with some lesser contribution from Au S . This picture is supported by density functional theory analysis of complex formation energies and diffusion barriers.
化学吸附物种可以增强纳米结构金属表面的流动动力学，这对催化等应用具有重要意义。室温下的扫描隧道显微镜研究表明，吸附硫（S）的存在极大地提高了Au(111)上扩展台阶边缘附近二维金岛的衰减速率。在硫覆盖率θ为百分之几单层（ML）时，这种增强效应就已经很显著，在0.1 - 0.3 ML时最为明显，此时衰减速率增加了约30倍。当θ在约0.6 ML接近饱和时，硫会导致整个表面出现点蚀和重构，金岛得以稳定。在较低θ时粗化增强归因于Au - S络合物（特别是AuS和Au₂S）在台面上的形成和扩散，Au₃S的贡献较小。这一图景得到了络合物形成能和扩散势垒的密度泛函理论分析的支持。
