Controlled Transformation of the Structures of Surface Fe (FeO) and Subsurface Fe on Pt(111)

Monolayer Fe films on Pt(111) and their derived structures under different environments were investigated by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). The growth of monolayer Fe films was seen at 487 K. The surface composition and structure of the Fe/Pt(111) surface were monitored by XPS and STM during stepwise annealing under vacuum. Surface Fe was driven into the subsurface region during annealing above 800 K. This resulted in a Pt-skin surface of Pt/Fe/Pt(111). Oxidation of the Pt-skin structure in O2 produced a FeO surface structure, FeO/Pt(111). This was transformed into a surface Fe structure by mild reduction in H2 (600 K) and into subsurface Fe by further severe reduction (800 K). The transformation of surface Fe (FeO) and subsurface Fe in Pt(111) was reversible in cycled oxidation and reduction treatments. The results demonstrated the controlled preparation of various Fe-Pt surfaces. This can be important for the design of high-performance and low-cost catalysts.

摘要利用扫描隧道显微镜䜕(STM)䜕和䜕X䜕射线光电子能谱䜕(XPS)䜕对䜕Pt(111)䜕表面制备的䜕Fe䜕单层薄膜及其在不同环境气氛条件下的多种结构进行了研究.䜕䜕在温度为䜕487䜕K䜕的䜕Pt(111)䜕表面制备出了完整的䜕Fe䜕单层薄膜Fe/Pt(111).䜕䜕对䜕Fe/Pt(111)䜕依次升高温度进行超高真空退火,䜕STM䜕和䜕XPS䜕结果表明退火温度高于䜕800 K䜕时,䜕表面䜕Fe䜕原子扩散到次表层区域,䜕形成次表层䜕Fe䜕结构Pt/Fe/Pt(111).䜕䜕Pt/Fe/Pt(111)䜕在䜕O2䜕氧化气氛中经䜕850 K䜕退火可转变成表面䜕FeO䜕薄膜FeO/Pt(111).䜕䜕FeO/Pt(111)䜕结构在温和的䜕H2䜕还原气氛中䜕(600 K)䜕转变成表面䜕Fe䜕结构,䜕进一步的还原处理䜕(800䜕K)䜕则可以重新生成䜕Pt/Fe/Pt(111).䜕䜕控制样品的环境气氛在䜕O2䜕和䜕H2䜕之间切换,䜕使得表面䜕Fe䜕(FeO)䜕和次表面䜕Fe䜕可以重复地转变.䜕䜕本研究实现了多种䜕Fe-Pt䜕表面结构的可控制备,䜕可为合理地设计高效、价廉的催化剂提供借鉴.

By changing temperature and gas environment of the sample, multiple structures of the Fe-Pt(111) system, surface Fe film or islands, subsurface Fe, and surface FeO, have been fully controllable.Figure optionsDownload as PowerPoint slide