| 摘要(英) |
Two separate subjects are addressed in this thesis. Part I describes cyclic voltammetry (CV) and in situ scanning tunneling microscopy (STM) results obtained with cysteine betaine adsorbed on a Au(111) electrode as a function of potential, anion and pH. In 0.1M perchloric acid, cysteine betaine was adsorbed mainly in stripe structures designated as(√21×√37) and((8×8) with a coverage (Ɵ) of 0.093 between 0.4 to 0.7V (vs. reversible hydrogen electrode). At 0.75V, these stripe structure transformed into a honeycomb-like structure characterized as (6×6), Ɵ = 0.083. Cysteine betaine molecule was oxidized at E > 0.8V. In 0.1M sulfuric acid, a structure(4×5), Ɵ = 0.2 consisted of betaine between 0.3 to 0.5V, but bisulfate anions competed with cysteine for adsorption on the Au(111) electrode, resulting in a pronounced order-to-disorder phase transition at 0.7V. This transition was quasi-reversible, as the stripe structure appeared again, once the potential was made to 0.3V. The main stripe structure became(√7×7) with a coverage of 0.19 at 0.3V, whose coverage is 5% lower than that of (4×5). At 0.6V, the stripe structure turned into two vertical structures(4√3×√21)and(√43×√21)with a coverage of 0.055 and 0.059 among a mainly disordered adlayer. To both perchloric acid and sulfuric acid, adding cysteine betaine 0.3μM resulted in stripe structures, (4×5) and (√7×7), between 0.3 to 0.5V. (8×5√3) and (4×3√3) structures (Ɵ = 0.0375 and 0.167) were found in sulfuric acid, which contrast (√21×12) and (4×4√3), (Ɵ = 0.133 and 0.125) in perchloric acid. Being a zwitterion ion, betaine is either positively charged or neutral when pH is lower or greater than 4.36. In pH3, 7, 10.9, and 12.67 media, in situ STM revealed (4×5),(√19×3√3)and(√7×7) and structures under proper potential control.
Part II addresses the decomposition of polyaniline (PANI) at positive potential and the conductivity of PANI using STM. Regardless of monolayer or multilayer PANI, CV results show decomposition between 0.9 to 1.4V by CV. PANI chains shortened at 0.92V and vastly degraded at 0.98V. The reversibility of PANI’s conformation between straight and crooked forms in sulfuric acid were examined in nitric acid, sulfuric acid, and perchloric acid. The conversion from crooked to straight form occurred at 0.88V in sulfuric acid, as opposed to 0.8V seen in nitric acid or perchloric acid. The conductivity of different conformation PANI measured by STM. Results show that poor correlation between conductivity and anions and variation with potential, in particular, conductivity decreased with more positive potential.
|
| 參考文獻 |
1. Luk, Y. Y.; Kato, M.; Mrksich, M. Self-assembled monolayers of alkanethiolates presenting mannitol groups are inert to protein adsorption and cell attachment. Langmuir 2000, 16 (24), 9604-9608.
2. Ostuni, E.; Chapman, R. G.; Holmlin, R. E.; Takayama, S.; Whitesides, G. M. A survey of structure-property relationships of surfaces that resist the adsorption of protein. Langmuir 2001, 17 (18), 5605-5620.
3. Liu, A. C.; Chen, D. C.; Lin, C. C.; Chou, H. H.; Chen, C. H. Application of cysteine monolayers for electrochemical determination of sub-ppb copper(II). Anal. Chem. 1999, 71 (8), 1549-1552.
4. Bigelow, W. C.; Pickett, D. L.; Zisman, W. A. Oleophobic monolayers: I. Films adsorbed from solution in non-polar liquids. Journal of Colloid Science 1946, 1 (6), 513-538.
5. Ulman, A. Formation and structure of self-assembled monolayers. Chem. Rev. 1996, 96 (4), 1533-1554.
6. Nuzzo, R. G.; Allara, D. L. Adsorption of bifunctional organic disulfides on gold surfaces. J. Am. Chem. Soc. 1983, 105 (13), 4481-4483.
7. Lee, S. H.; Lin, W. C.; Kuo, C. H.; Karakachian, M.; Lin, Y. C.; Yu, B. Y.; Shyue, J. J. Photooxidation of Amine-Terminated Self-Assembled Monolayers on Gold. J. Phys. Chem. C 2010, 114 (23), 10512-10519.
8. Kuhnle, A.; Linderoth, T. R.; Hammer, B.; Besenbacher, F. Chiral recognition in dimerization of adsorbed cysteine observed by scanning tunnelling microscopy. Nature 2002, 415 (6874), 891-893.
9. Dakkouri, A. S.; Kolb, D. M.; EdelsteinShima, R.; Mandler, D. Scanning tunneling microscopy study of L-cysteine an Au(111). Langmuir 1996, 12 (11), 2849-2852.
10. Xu, Q. M.; Wan, L. J.; Wang, C.; Bai, C. L.; Wang, Z. Y.; Nozawa, T. New structure of L-cysteine self-assembled monolayer on Au(111): Studies by in situ scanning tunneling microscopy. Langmuir 2001, 17 (20), 6203-6206.
11. Zhang, J. D.; Chi, Q. J.; Nielsen, J. U.; Friis, E. P.; Andersen, J. E. T.; Ulstrup, J. Two-dimensional cysteine and cystine cluster networks on Au(111) disclosed by voltammetry and in situ scanning tunneling microscopy. Langmuir 2000, 16 (18), 7229-7237.
12. Zhang, H. M.; Su, G. J.; Wang, D.; Wan, L. J.; Jin, G.; Bai, C. L.; Zhou, Z. L. Adlayer structures of DL-homocysteine and L-homocysteine thiolactone on Au(111) surface: an in situ STM study. Electrochim. Acta 2004, 49 (9-10), 1629-1633.
13. Zhang, J. D.; Demetriou, A.; Welinder, A. C.; Albrecht, T.; Nichols, R. J.; Ulstrup, J. Potential-induced structural transitions of DL-homocysteine monolayers on Au(111) electrode surfaces. Chem. Phys. 2005, 319 (1-3), 210-221.
14. Yanson, Y.; Frenken, J. W. M.; Rost, M. J. A general model of metal underpotential deposition in the presence of thiol-based additives based on an in situ STM study. PCCP 2011, 13 (35), 16095-16103.
15. 陳思孜. 利用掃描式電子穿隧顯微鏡探討聚苯胺及其衍生物在金(111)電極上之吸附與構型變化. 國立中央大學, 桃園縣, 2014.
16. Yan, J. W.; Ouyang, R. H.; Jensen, P. S.; Ascic, E.; Tanner, D.; Mao, B. W.; Zhang, J. D.; Tang, C. G.; Hush, N. S.; Ulstrup, J.; Reimers, J. R. Controlling the Stereochemistry and Regularity of Butanethiol Self-Assembled Mono layers on Au(111). J. Am. Chem. Soc. 2014, 136 (49), 17087-17094.
|
[Endnote RIS 格式]
[相關文章]
[文章引用]
[完整記錄]
[館藏目錄]
[檢視]
plurk
funp
live
udn
HD
myshare
netvibes
friend
youpush
delicious
baidu
Google bookmarks
del.icio.us
hemidemi
facebook
twitter
google
reddit