Electric double layer of Au(100)/imidazolium-based ionic liquids interface: Effect of cation size

We have carried out differential capacitance measurements and in-situ scanning tunneling microscope (STM) characterizations to investigate the effect of the length of alkyl side chains on an electric double layer of Au(100)/imidazolium-based ionic liquids interface. In ionic liquids consisting of BMI+ cation (1-butyl-3-methylimidazolium), differential capacitance curves present an obvious bell-shaped feature. In ionic liquids with PMI+ (1-methyl-3-propylimidazolium) or OMI+ (1-methyl-3-octylimidazolium) cations, the rising of capacitance from about -0.5 V disturbs the bell-shaped feature. In-situ STM characterizations reveal the generality of surface etching and micelle-like adsorption of imidazolium cations on Au(100) at potential around the peaks of the bell-shaped feature, demonstrating that the potential of zero charge (PZC) should locate at the potential close to the peaks. Because of the longer side chain length and stronger interaction with Au(100) substrate, an extra capacitance peak appears at the potential as negative as -1.65 V in OMIPF6 and a corresponding order-disorder transformation of OMI+ cation adlayer is revealed by STM, indicating a correlation between differential capacitance curve and STM. ? 2012 American Chemical Society

STM Study on Nonionic Fluorosurfactant Zonyl FSN Self-Assembly on Au(100): (3/11/1) Molecular Lattice, Corrugations, and Adsorbate-Enhanced Mobility

Nonionic fluorosurfactant zonyl FSN self-assembly on Au(100) is investigated by using scanning tunneling microscopy under ambient conditions. High-resolution STM images reveal that a [GRAPHICS] arrangement of the FSN SAMs is formed on Au(100). Different from the uniform structure of FSN SAMs on Au(111), the adsorption sites of FSN molecules on Au(100) change gradually and form a kind of corrugated structure. The change in the adsorption sites probably originates from the repulsive force among FSN molecules because the nearest-neighbor distance of FSN molecules is 0.41 nm, which is smaller than 0.50 nm on Au(111). The mobility of surface atoms on the Au substrate is enhanced by the interaction between FSN molecules and the Au substrate; therefore, no Au island is observed on the FSN-SAM-covered Au(100).Natural Science Foundation of China (NSFC) [20973144]; SRF for ROCS, SEM, China [2008-890]; Special Funds for Major State Basic Research Project of China [2007CB935600, 2009CB220102

Electric Double Layer of Au(100)/Imidazolium-Based Ionic Liquids Interface: Effect of Cation Size

We have carried out differential capacitance measurements and in-situ scanning tunneling microscope (STM) characterizations to investigate the effect of the length of alkyl side chains on an electric double layer of Au(100)/imidazolium-based ionic liquids interface. In ionic liquids consisting of BMI+ cation (1-butyl-3-methylimidazolium), differential capacitance curves present an obvious bell-shaped feature. In ionic liquids with PMI+ (1-methyl-3-propylimidazolium) or OMI+ (1-methyl-3-octylimidazolium) cations, the rising of capacitance from about -0.5 V disturbs the bell-shaped feature. In-situ STM characterizations reveal the generality of surface etching and micelle-like adsorption of imidazolium cations on Au(100) at potential around the peaks of the bell-shaped feature, demonstrating that the potential of zero charge (PZC) should locate at the potential close to the peaks. Because of the longer side chain length and stronger interaction with Au(100) substrate, an extra capacitance peak appears at the potential as negative as -1.65 V in OMIPF6 and a corresponding order-disorder transformation of OMI+ cation adlayer is revealed by STM, indicating a correlation between differential capacitance curve and STM

Electric Double Layer of Au(100)/Imidazolium-Based Ionic Liquids Interface: Effect of Cation Size

We have carried out differential capacitance measurements and in-situ scanning tunneling microscope (STM) characterizations to investigate the effect of the length of alkyl side chains on an electric double layer of Au(100)/imidazolium-based ionic liquids interface. In ionic liquids consisting of BMI⁺ cation (1-butyl-3-methylimidazolium), differential capacitance curves present an obvious bell-shaped feature. In ionic liquids with PMI⁺ (1-methyl-3-propylimidazolium) or OMI⁺ (1-methyl-3-octylimidazolium) cations, the rising of capacitance from about −0.5 V disturbs the bell-shaped feature. In-situ STM characterizations reveal the generality of surface etching and micelle-like adsorption of imidazolium cations on Au(100) at potential around the peaks of the bell-shaped feature, demonstrating that the potential of zero charge (PZC) should locate at the potential close to the peaks. Because of the longer side chain length and stronger interaction with Au(100) substrate, an extra capacitance peak appears at the potential as negative as −1.65 V in OMIPF₆ and a corresponding order–disorder transformation of OMI⁺ cation adlayer is revealed by STM, indicating a correlation between differential capacitance curve and STM