Scanning tunnelling microscopy study of the growth of small palladium particles on TiO2(110)

Abstract We studied the thermal stability of small palladium clusters on a TiO 2 (110) surface. Upon heating the number of particles decreases and the average size of the particles increases. This corresponds to a decrease of palladium surface area of this model catalyst. The decrease in particle density cannot be used to distinguish between different kinds of mass transport over the surface, but on the basis of the resulting size distribution we conclude that the coalescence of diffusing particles is the main mechanism. This is supported by a direct observation of mobile clusters. During growth the palladium clusters change their shape.

[1]  B. Hayden,et al.  The adsorption of carbon monoxide on TiO 2(110) supported palladium , 1996 .

[2]  E. E. Gruber.  Calculated Size Distributions for Gas Bubble Migration and Coalescence in Solids , 1967 .

[3]  H. Poppa.  Nucleation, Growth, and TEM Analysis of Metal Particles and Clusters Deposited in UHV , 1993 .

[4]  J. A. Venables,et al.  Rate equation approaches to thin film nucleation kinetics , 1973 .

[5]  K. Fukui,et al.  Atomic-Scale Surface Structures of TiO2(110) Determined by Scanning Tunneling Microscopy: A New Surface-Limited Phase of Titanium Oxide , 1995 .

[6]  Charles T. Campbell,et al.  Ultrathin metal films and particles on oxide surfaces: structural, electronic and chemisorptive properties , 1997 .

[7]  B. Chakraverty.  Grain size distribution in thin films—1. Conservative systems , 1967 .

[8]  J. Venables,et al.  Growth of nanometer‐size metallic particles on CaF2(111) , 1996 .

[9]  M. Zinke–Allmang,et al.  Ordering of clusters during late-stage growth on surfaces , 1997 .

[10]  L. Feldman,et al.  Clustering on surfaces , 1992 .

[11]  G. Thornton,et al.  Added row model of TiO2(110)1x2 , 1998 .

[12]  I. Lifshitz,et al.  The kinetics of precipitation from supersaturated solid solutions , 1961 .

[13]  Stroscio,et al.  Scaling of diffusion-mediated island growth in iron-on-iron homoepitaxy. , 1994, Physical review. B, Condensed matter.

[14]  Theis,et al.  Chemical potential maps and spatial correlations in 2D-island ripening on Si(001). , 1995, Physical review letters.

[15]  M. Lagally,et al.  Surface self-diffusion of Si on Si(001) , 1992 .

[16]  D. Goodman,et al.  Scanning tunneling microscopy studies of the TiO 2 ( 110 ) surface: Structure and the nucleation growth of Pd , 1997 .

[17]  M. Kuhn,et al.  Intrinsic defects on a TiO2(110)(1×1) surface and their reaction with oxygen: a scanning tunneling microscopy study , 1998 .

[18]  D. Bonnell,et al.  A scanning tunneling microscopy and spectroscopy study of the TiO2−x(110) surface , 1992 .

[19]  John Meurig Thomas.  Principles and practice of heterogeneous catalysis , 1996 .

[20]  M. Hoogeman,et al.  On the smoothing of rough surfaces , 1999 .

[21]  M. Bäumer,et al.  Metal deposits on well-ordered oxide films , 1999 .

[22]  P. Harris.  Growth and structure of supported metal catalyst particles , 1995 .

[23]  Eli Ruckenstein,et al.  Growth kinetics and the size distributions of supported metal crystallites , 1973 .

[24]  G. Mills,et al.  A new method for simulating the late stages of island coarsening in thin film growth: The role of island diffusion and evaporation , 1999 .

[25]  J. T. Ranney,et al.  The Surface Science of Metal Oxides , 1995 .

[26]  M. Bowker,et al.  TWO (1 X 2) RECONSTRUCTIONS OF TIO2(110) : SURFACE REARRANGEMENT AND REACTIVITY STUDIED USING ELEVATED TEMPERATURE SCANNING TUNNELING MICROSCOPY , 1999 .

[27]  J. Venables,et al.  Nucleation and growth of supported metal clusters at defect sites on oxide and halide (0 0 1) surfaces , 2000 .

[28]  Rosenfeld,et al.  Brownian motion of vacancy islands on Ag(111). , 1995, Physical review letters.

[29]  J. Venables,et al.  Nucleation and growth of thin films , 1984 .

[30]  Murray,et al.  Effect of stoichiometry on the structure of TiO2(110). , 1995, Physical review. B, Condensed matter.

[31]  A. Datye,et al.  The study of heterogeneous catalysts by high-resolution transmission electron microscopy , 1992 .

[32]  C. H. Bartholomew.  Sintering kinetics of supported metals: new perspectives from a unifying GPLE treatment , 1993 .

[33]  Theis,et al.  Ostwald ripening of two-dimensional islands on Si(001). , 1996, Physical review. B, Condensed matter.

[34]  Joost W. M. Frenken,et al.  Design and performance of a high‐temperature, high‐speed scanning tunneling microscope , 1995 .

[35]  D. Goodman,et al.  Onset of catalytic activity of gold clusters on titania with the appearance of nonmetallic properties , 1998, Science.

[36]  Iwasawa,et al.  Dynamic visualization of a metal-oxide-surface/gas-phase reaction: Time-resolved observation by scanning tunneling microscopy at 800 K. , 1996, Physical review letters.

[37]  N. Bartelt,et al.  Diffusion of monolayer adatom and vacancy clusters: Langevin analysis and Monte Carlo simulations of their Brownian motion. , 1995, Physical review letters.

[38]  Claude R. Henry,et al.  Surface studies of supported model catalysts , 1998 .

[39]  Dimo Kashchiev,et al.  Kinetics of thin film coalescence due to crystallite surface migration , 1976 .