Epitaxial growth of bimetallic Au-Cu nanoparticles on TiO2(110) followed in situ by scanning tunneling microscopy and grazing-incidence x-ray diffraction

A. Wilson (1) , Romain Bernard (1) , Adriana Vlad , Yves Borensztein (1) , A. Coati (2) , Bernard Croset (1) , Y. Garreau , Geoffroy Prévot (1)

1 INSP - Institut des Nanosciences de Paris
2 SSOLEIL - Synchrotron SOLEIL

Scanning tunneling microscopy (STM) and grazing-incidence x-ray diffraction (GIXD) have been used to follow in situ the growth and the structure of Au-Cu nanoparticles (NPs) formed on TiO2(110) by successive metal evaporations. STM observations of the same area of the substrate highlight the strong dependence between the sequence of deposition and the final result. Deposition of Cu first leads to a system where both Au-Cu and pure Au NPs coexist. Deposition of Au first ensures growing mostly bimetallic NPs. GIXD results show that Cu alloys instantaneously with Au NPs at room temperature. Similar observations during evaporation of Au on Cu NPs show that some of the Au atoms alloy with Cu whereas the rest remain at the NP shell. This is attributed both to kinetics and thermodynamics origins.

Domaines: Matière Condensée [cond-mat]

A. Wilson, Romain Bernard, Adriana Vlad, Yves Borensztein, A. Coati, et al.. Epitaxial growth of bimetallic Au-Cu nanoparticles on TiO2(110) followed in situ by scanning tunneling microscopy and grazing-incidence x-ray diffraction. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2014, 90 (7), pp.075416. ⟨10.1103/PhysRevB.90.075416⟩. ⟨hal-01238953⟩