Subscriber access provided by SUNY OSWEGO
C: Surfaces, Interfaces, Porous Materials, and Catalysis
Quantitative Analysis of Catalysis and SERS Performance in Star and Hollow Shaped Au Nanostructures Kamalesh Nehra, Senthil Kumar Pandian, Chandu Byram, Moram Sree Satya Bharati, and Venugopal Rao Soma J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.9b03086 • Publication Date (Web): 06 Jun 2019 Downloaded from http://pubs.acs.org on June 6, 2019
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 43 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
The Journal of Physical Chemistry
Quantitative Analysis of Catalysis and SERS Performance in Star and Hollow Shaped Au Nanostructures Kamalesh Nehra,1 Senthil Kumar Pandian, 1,* Chandu Byram, 2 Sree Satya Bharati Moram, 2and Venugopal Rao Soma2, # 1Department 2Advanced
of Physics and Astrophysics, University of Delhi, Delhi110007, India
Centre for Research in High Energy Materials (ACRHEM), University of Hyderabad, Prof. C. R. Rao Road, Hyderabad 500046, Telangana, India
* Author e-mail:
[email protected] # Corresponding Author e-mail:
[email protected];
[email protected] ABSTRACT Surface roughness of the metal nanoparticles is well-known to play an important role in the quantitative analysis and performance of their SERS performances but their analogous role in catalysis is not given the due credit yet. In the present work, we systematically investigated this by utilizing two significantly relevant gold (Au) nanostructures - the hollow and the star shaped in a comprehensive manner. For catalysis, the universal model reaction, the reduction of pnitroaniline (p-NA) to PDA using NaBH4, was engaged and SERS measurements were performed by employing methylene blue as the standard analyte molecule. At the outset, the predominantly fascinating role of the nanoparticle surface area in conjunction with surface roughness in catalysis was carefully evaluated for our robustly synthesized Au hollow nanoparticles (NPs), possessing an inherent thin inner core layer of Ag, and star shaped Au NPs 1 ACS Paragon Plus Environment
The Journal of Physical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
along with two different sized solid spherical Au NPs. As expected, improved performances were observed in all the above nanoparticles, but with subtle differences. Even though the observed catalytic reaction rate constant was higher in the smaller sized solid Au NPs, it evidently followed the first-order reaction kinetics throughout: whereas, in the case of star shaped Au NPs, the rate constant was relatively higher, yet the reaction kinetics was found to be of first order in nature, essentially envisaging the fact that increasing the catalytic surface area along with roughness solely enhances the reaction rate, but not the kinetics. Nevertheless, when hollow Au NPs were used, not only the reaction completed in a much lesser time, the reaction behaviour also followed the drastically different path, i.e. zeroth order kinetics - extensively attributed to the presence of interior cavity in the case of hollow Au NPs - thereby substantiating the increased surface area. A complementary trend was observed in the SERS applications, wherein the solid spherical and hollow Au NPs demonstrated detection up to nM concentration of methylene blue dye molecules (corresponding enhancement factor of ~106), in direct contrast with the star shaped Au NPs, which meticulously detected even
