47226-GB5
Chiral Recognition of PVBA on fcc(111) Surfaces in Electrochemical Solutions
The project aims to enhance the basic understanding of the influence of solvent and thermal energy on chiral recognition of 4-trans-2-(pyrid-4-yl-vynyl) benzoic acid (PVBA) on Pd(111) and Ag(111) by electrochemical scanning tunneling microscopy (EC-STM) in contrast to the previous ultra-high vacuum (UHV) based studies.
The PI and his five undergraduate students have made the following progress during the first year of ACS-PRF funding:
1. Set-up of EC-STM and Potentiostat: The PI and his students combined a potentiostat EG&G 273 (Princeton Applied Research) with the VEECO (
2. Tip Preparation: The tungsten tip was etched electrochemically in 10% KOH solution and was dipped in a hydrofluoric solution for a few minutes to remove any residual oxide on the tip surface. Subsequently, the tip was coated with a commercial nail varnish for the electrical insulation of the tip body from the electrochemical solution to avoid the electrochemical charge transfer reactions or Faraday current.
3. Preparation of Electrodes: Ag and Pt electrodes were used as the reference and counter electrodes, respectively. The Ag wire was cleaned with acetone and stored for three days in 3M H2SO4. Cyclic voltammetry curves were acquired by using the electrochemical cell for in situ EC-STM measurements.
4. EC-STM on a well-defined graphite surface: The PI and his undergraduate research assistants tested the EC STM on highly oriented pyrolitic Graphite (HOPG) with the prepared tungsten tip in perchloric acid (HClO4 + H2O). Cyclic voltammetry was first performed on a HOPG basal plane to observe the intercalation process, which occured through natural steps. The typical cyclic voltammetry curve was consistent with those curves reported in the literature, demonstrating the adequacy of the potentiostat to conduct the research. The EC STM was performed on the same surface in 2 M HClO4 at the potential of working electrode, 0 mV, vs the silver reference electrode. The atomic-step structures are clearly resolved between two terraces on the HOPG surface in the electrochemical solution.
5. EC-STM on a well-defined Au surface: Atomic resolution images were also successfully obtained on a flamed annealed Au (111) surface by the EC-STM. The result demonstrated the feasibility of the PI’s EC-STM for PVBA chiral recognition studies on fcc(111) surfaces in electrochemical environments.
We are currently investigating the influence of solvent and thermal energy on the chiral recognition of PVBA on Pd(111) and Ag(111) using the EC-STM which has been successfully developed during the first-year of the ACS-PRF grant funding.
Impact on the PI’s Career: The ACS-PRF support increased the research and education facilities and opportunities for the interdisciplinary undergraduate students, which is an important addition to the PI’s research program at
Impact on the students: The five undergraduate students have been actively involved in this project under the guidance of the PI. The development of EC-STM provided undergraduate students with an excellent opportunity to receive in-depth learning experience in nano- and bio-science so that they will be better prepared to compete for placement in graduate programs or careers in the nano/biotech industry. Undergraduate students participating in this project have learned to design sophisticated scientific instrumentation. So far, the undergraduate students have presented their results at the four state-wide and on-campus undergraduate conferences.
