TY - JOUR
T1 - High resolution electrochemical STM
T2 - New structural results for underpotentially deposited Cu on Au(1 1 1) in acid sulfate solution
AU - Vasiljevic, Natasa
AU - Viyannalage, Lasantha T.
AU - Dimitrov, Nikolay
AU - Sieradzki, Karl
PY - 2008/2/15
Y1 - 2008/2/15
N2 - Adsorption of sulfate assists Cu monolayer underpotential deposition (upd) on Au(1 1 1) in a unique way, rendering two distinct structural stages: (i) formation of a low-density Cu phase at coverage of 2/3 ML known as the fenced(sqrt(3) × sqrt(3)) R 30 ° or honeycomb phase; (ii) formation of a complete monolayer, i.e., Cu-(1 × 1) phase pseudomorphic with respect to underlying Au(1 1 1) substrate. In this paper we present new structural in situ scanning tunneling microscopy (STM) results for this system. We show and discuss the STM imaging of the copper honeycomb superstructure probed underneath the co-adsorbed fenced(sqrt(3) × sqrt(3)) R 30 ° sulfate adlayer in the low-density phase. High resolution imaging during the phase transition from the low to high density copper phase unambiguously shows the existence of an ordered sulfate structure p(2 × 2) on the pseudomorphic Cu-(1 × 1) layer. The new structure is seen during the co-existence of two copper phases as well as upon completion of the Cu-(1 × 1) monolayer. While supported by earlier chronocoulometric measurements in the same system, the new structural results raise questions that need to be addressed in a future work.
AB - Adsorption of sulfate assists Cu monolayer underpotential deposition (upd) on Au(1 1 1) in a unique way, rendering two distinct structural stages: (i) formation of a low-density Cu phase at coverage of 2/3 ML known as the fenced(sqrt(3) × sqrt(3)) R 30 ° or honeycomb phase; (ii) formation of a complete monolayer, i.e., Cu-(1 × 1) phase pseudomorphic with respect to underlying Au(1 1 1) substrate. In this paper we present new structural in situ scanning tunneling microscopy (STM) results for this system. We show and discuss the STM imaging of the copper honeycomb superstructure probed underneath the co-adsorbed fenced(sqrt(3) × sqrt(3)) R 30 ° sulfate adlayer in the low-density phase. High resolution imaging during the phase transition from the low to high density copper phase unambiguously shows the existence of an ordered sulfate structure p(2 × 2) on the pseudomorphic Cu-(1 × 1) layer. The new structure is seen during the co-existence of two copper phases as well as upon completion of the Cu-(1 × 1) monolayer. While supported by earlier chronocoulometric measurements in the same system, the new structural results raise questions that need to be addressed in a future work.
KW - Anion adsorption
KW - Copper, Au(1 1 1)
KW - In situ scanning tunneling microscopy
KW - Sulfate
KW - Underpotential deposition
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U2 - 10.1016/j.jelechem.2007.10.021
DO - 10.1016/j.jelechem.2007.10.021
M3 - Article
AN - SCOPUS:38849137888
SN - 1572-6657
VL - 613
SP - 118
EP - 124
JO - Journal of Electroanalytical Chemistry
JF - Journal of Electroanalytical Chemistry
IS - 2
ER -