采用扫描隧道显微镜和X射线光电子能谱对含有次表层Fe的Pt表皮结构(Pt skin),即0.4MLFe的Pt/Fe/Pt(111)表面,在1.1×10-7kPa氧气气氛退火过程中的变化进行了研究.结果表明,当退火温度为600K时,氧气在Pt/Fe/Pt(111)表面上解离吸附并诱导表面局域结构的重构;750K时次表层Fe可以扩散到表面并被氧化;当升至850K时,在样品表面形成单层FeO结构,并且FeO表面具有周期性的缺陷.这种缺陷是由于单层FeO薄膜的摩尔条纹单胞中fcc位上一个或多个氧原子缺失形成的,其中多原子空位被确定为缺失6个氧原子所致.FeO表面缺陷结构的研究为理解Fe-Pt催化剂在氧化气氛中的结构稳定性以及构造表面活性位提供一定的基础.
The structural evolution of a Pt surface with 0.4 monolayer (ML) subsurface Fe on annealing in 1.1 × 10-7 kPa O2 was studied by scanning tunneling microscopy and X-ray photoelectron spectroscopy. When the annealing temperature was 600 K, only dissociative adsorption of O2 occurred, which induced the local restructuring of surface regions. At 750 K, subsurface Fe atoms segregated onto the surface and were oxidized. When the annealing temperature was increased to 850 K, well defined monolayer FeO islands with periodic arrays of defects vacancies or multiple oxygen vacancies consisting of six missing O atoms. The formation of periodic defects on monolayer FeO islands may be a way to construct active sites on Pt-Fe model catalysts.
参考文献
| [1] | Stamenkovic VR;Fowler B;Mun BS;Wang GF;Ross PN;Lucas CA;Markovic NM .Improved oxygen reduction activity on Pt3Ni(111) via increased surface site availability[J].Science,2007(26):493-497. |
| [2] | Koh S;Leisch J;Toney M F;Strasser P .[J].Journal of Physical Chemistry C,2007,111:3744. |
| [3] | Srivastava R;Mani P;Hahn N;Strasser P .[J].Angewandte Chemie International Edition,2007,46:8988. |
| [4] | Toda T;Igarashi H;Watanabe M .[J].Journal of Electroanalytical Chemistry,1999,460:258. |
| [5] | Murillo, LE;Goda, AM;Chen, JG .Selective hydrogenation of the CO bond in acrolein through the architecture of bimetallic surface structures[J].Journal of the American Chemical Society,2007(22):7101-7105. |
| [6] | Su H Y;Bao X H;Li W X .[J].Journal of Chemical Physics,2008,128:194707. |
| [7] | Stamenkovic V;Mun B S;Mayrhofer K J J;Ross P N,Markovic N M,Rossmeisl J,Greeley J,Norskov J K .[J].Angewandte Chemie International Edition,2006,45:2897. |
| [8] | Stamenkovic VR;Mun BS;Arenz M;Mayrhofer KJJ;Lucas CA;Wang GF;Ross PN;Markovic NM .Trends in electrocatalysis on extended and nanoscale Pt-bimetallic alloy surfaces[J].Nature materials,2007(3):241-247. |
| [9] | 马腾,傅强,崔义,张镇,王珍,谭大力,包信和.Pt（111）表面上表层Fe（FeO）结构和次表层Fe结构的可控转变[J].催化学报,2010(01):24-32. |
| [10] | Tao F;Grass M E;Zhang Y W;Butcher D R Renzas J R Liu Z Chung J Y Mun B S Salmeron M Somorjai G A .[J].Science,2008,322:932. |
| [11] | Menning C A;Hwu H H;Chen J G .[J].Journal of Physical Chemistry B,2006,110:15471. |
| [12] | Knudsen J;Nilekar AU;Vang RT;Schnadt J;Kunkes EL;Dumesic JA;Mavrikakis M;Besenbacher F .A Cu/Pt near-surface alloy for water-gas shift catalysis[J].Journal of the American Chemical Society,2007(20):6485-6490. |
| [13] | Khan N A;Murillo L E;Chen J G .[J].Journal of Physical Chemistry B,2004,108:15748. |
| [14] | Ma, T;Fu, Q;Su, HY;Liu, HY;Cui, Y;Wang, Z;Mu, RT;Li, WX;Bao, XH .Reversible Structural Modulation of Fe-Pt Bimetallic Surfaces and Its Effect on Reactivity[J].Chemphyschem: A European journal of chemical physics and physical chemistry,2009(7):1013-1016. |
| [15] | Gland J L;Sexton B A;Fisher G B .[J].Surface Science,1980,95:587. |
| [16] | Stipe BC.;Ho W.;Rezaei MA. .ATOMISTIC STUDIES OF O-2 DISSOCIATION ON PT(111) INDUCED BY PHOTONS, ELECTRONS, AND BY HEATING[J].The Journal of Chemical Physics,1997(16):6443-6447. |
| [17] | Weiss W.;Ritter M. .Metal oxide heteroepitaxy: Stranski-Krastanov growth for iron oxides on Pt(111)[J].Physical Review.B.Condensed Matter,1999(7):5201-5213. |
| [18] | Kim YJ.;Ynzunza RX.;Wang Z.;Galloway HC.;Salmeron M.;Van Hove MA.;Fadley CS.;Westphal C. .The growth of iron oxide films on Pt(111): a combined XPD, STM, and LEED study[J].Surface Science: A Journal Devoted to the Physics and Chemistry of Interfaces,1998(1/2):68-111. |
| [19] | Galloway HC.;Salmeron M.;Sautet P. .STRUCTURE AND CONTRAST IN SCANNING TUNNELING MICROSCOPY OF OXIDES - FEO MONOLAYER ON PT(111)[J].Physical Review.B.Condensed Matter,1996(16):11145-11148. |
| [20] | Giordano L;Pacchioni G;Goniakowski J;Nilius N Rienks E D L Freund H J .[J].Physical Review B:Condensed Matter,2007,76:075416. |
| [21] | Ritter M.;Weiss W.;Ranke W. .Growth and structure of ultrathin FeO films on Pt(111) studied by STM and LEED[J].Physical Review.B.Condensed Matter,1998(12):7240-7251. |
| [22] | Fu Q;Li W X;Yao Y X;Liu H Y Su H Y Ma D Gu X K Chen L M Wang Z Zhang H Wang B Bao X H .[J].Science,2010,328:1141. |
| [23] | Zhang W H;Li Z Y;Luo Y;Yang J L .[J].Journal of Physical Chemistry C,2009,113:8302. |
| [24] | Merte L R;Knudsen J;Grabow L C;Vang R T Leasgaard E Mavrikakis M Besenbacher F .[J].Surface Science,2009,603:L15. |
| [25] | Huang WX;Ranke W .Autocatalytic partial reduction of FeO(111) and Fe3O4(111) films by atomic hydrogen[J].Surface Science: A Journal Devoted to the Physics and Chemistry of Interfaces,2006(4):793-802. |
| [26] | Yao Y X;Fu Q;Wang Z;Tan D L,Bao X H.[J].Journal of Physical Chemistry C |
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%