Nanoclusters and nanolines: the effect of molybdenum oxide substrate stoichiometry on iron self-assembly

The growth of Fe nanostructures on the stoichiometric MoO2/Mo(110) and oxygen-rich MoO2+x/Mo(110) surfaces has been studied using low-temperature scanning tunnelling microscopy (STM) and density functional theory calculations. STM results indicate that at low coverage Fe nucleates on the MoO2/Mo(110) surface, forming small, well-ordered nanoclusters of uniform size, each consisting of five Fe atoms. These five-atom clusters can agglomerate into larger nanostructures reflecting the substrate geometry, but they retain their individual character within the structure. Linear Fe nanocluster arrays are formed on the MoO2/Mo(110) surface at room temperature when the surface coverage is greater than 0.6 monolayers. These nanocluster arrays follow the direction of the oxide rows of the strained MoO2/Mo(110) surface. Slightly altering the preparation procedure of MoO2/Mo(110) leads to the presence of oxygen adatoms on this surface. Fe deposition onto the oxygen-rich MoO2+x/Mo(110) surface results in elongated nanostructures that reach up to 24 nm in length. These nanolines have a zigzag shape and are likely composed of partially oxidised Fe formed upon reaction with the oxygen-rich surface.

[1]  F. Calle‐Vallejo,et al.  Double-Stranded Water on Stepped Platinum Surfaces. , 2016, Physical review letters.

[2]  Chengzhou Zhu,et al.  Electrochemical Sensors and Biosensors Based on Nanomaterials and Nanostructures , 2014, Analytical chemistry.

[3]  Sheng Chen,et al.  Shape Control of Mn3O4 Nanoparticles on Nitrogen‐Doped Graphene for Enhanced Oxygen Reduction Activity , 2014 .

[4]  I. Shvets,et al.  Fabrication of [001]-oriented tungsten tips for high resolution scanning tunneling microscopy , 2014, Scientific Reports.

[5]  Brendan Bulfin,et al.  Writing with atoms: Oxygen adatoms on the MoO2/Mo(110) surface , 2013, Nano Research.

[6]  Zhen-an Qiao,et al.  Shape-controlled ceria-based nanostructures for catalysis applications. , 2013, ChemSusChem.

[7]  Christopher B. Murray,et al.  Control of Metal Nanocrystal Size Reveals Metal-Support Interface Role for Ceria Catalysts , 2013, Science.

[8]  J. Jennings.  Catalytic Ammonia Synthesis: Fundamentals And Practice , 2013 .

[9]  Jun Jiang,et al.  Nanostructured metal chalcogenides: synthesis, modification, and applications in energy conversion and storage devices. , 2013, Chemical Society reviews.

[10]  D. Tryk,et al.  Direct STM elucidation of the effects of atomic-level structure on Pt(111) electrodes for dissolved CO oxidation. , 2013, Journal of the American Chemical Society.

[11]  G. Somorjai,et al.  Size and Shape Control of Metal Nanoparticles for Reaction Selectivity in Catalysis , 2012 .

[12]  I. Shvets,et al.  Self-assembly of Fe nanocluster arrays on templated surfaces , 2012 .

[13]  I. Shvets,et al.  Selecting the tip electron orbital for scanning tunneling microscopy imaging with sub-ångström lateral resolution , 2010 .

[14]  B. Alder,et al.  THE GROUND STATE OF THE ELECTRON GAS BY A STOCHASTIC METHOD , 2010 .

[15]  F. Besenbacher,et al.  STM studies of model catalysts , 2007 .

[16]  I. Shvets,et al.  Epitaxial molybdenum oxide grown on MO (110): LEED, STM, and density functional theory calculations , 2007 .

[17]  H. Topsøe.  The role of Co–Mo–S type structures in hydrotreating catalysts , 2007 .

[18]  Zhong Lin Wang.  Novel nanostructures of ZnO for nanoscale photonics, optoelectronics, piezoelectricity, and sensing , 2007 .

[19]  Charles T Campbell,et al.  Transition metal oxides: extra thermodynamic stability as thin films. , 2006, Physical review letters.

[20]  A. Stierle,et al.  Structure of a thin oxide film on Rh(100) , 2005 .

[21]  D. Goodman,et al.  The stabilization of supported gold clusters by surface defects , 2005 .

[22]  S. Shiraki,et al.  Investigation of the electronic interaction between TiO2(110) surfaces and Au clusters by PES and STM , 2004 .

[23]  N. Yao,et al.  Scanning probe microscopy in catalysis. , 2004, Journal of nanoscience and nanotechnology.

[24]  J. Gustafson,et al.  Self-limited growth of a thin oxide layer on Rh(111). , 2004, Physical review letters.

[25]  A. Bell.  The Impact of Nanoscience on Heterogeneous Catalysis , 2003, Science.

[26]  M. V. Ganduglia-Pirovano,et al.  Role of subsurface oxygen in oxide formation at transition metal surfaces. , 2002, Physical review letters.

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

[28]  Kresse,et al.  Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. , 1996, Physical review. B, Condensed matter.

[29]  W. R. Peterson,et al.  THE OXIDATION OF METHANOL WITH AIR OVER IRON, MOLYBDENUM, AND IRON-MOLYBDENUM OXIDES , 1931 .

[30]  Z. Fan,et al.  Nanomaterials and nanostructures for efficient light absorption and photovoltaics , 2012 .

[31]  Younan Xia,et al.  A comparison study of the catalytic properties of Au-based nanocages, nanoboxes, and nanoparticles. , 2010, Nano letters.

[32]  Ulrike Diebold,et al.  The surface science of titanium dioxide , 2003 .