Letter pubs.acs.org/jchemeduc
Comment on “Shining Light on Nanochemistry Using Silver Nanoparticle-Enhanced Luminol Chemiluminescence” Muthupandian Ashokkumar*,† and Sambandam Anandan‡ †
School of Chemistry, University of Melbourne, Melbourne, Victoria 3010, Australia Nanomaterials and Solar Energy Conversion Lab, Department of Chemistry, National Institute of Technology, Trichy 620 015, India
Downloaded by CENTRAL MICHIGAN UNIV on September 11, 2015 | http://pubs.acs.org Publication Date (Web): September 10, 2015 | doi: 10.1021/acs.jchemed.5b00590
‡
ABSTRACT: An article: Panzarasa, G. J. Chem. Educ. 2014, 91 (5), 696−700; DOI: 10.1021/ed400736k, provides misleading information on a fundamental concept dealing with catalysis. KEYWORDS: General Public, High School/Introductory Chemistry, First-Year Undergraduate/General, Second-Year Undergraduate, Chemical Education Research e would like to comment on the article “Shining Light on Nanochemistry Using Silver Nanoparticle-Enhanced Luminol Chemiluminescence”.1 The article reports (ref 1, p 696): The aim of this demonstration is to combine the appealing character of chemiluminescent reactions with the catalytic properties displayed by noble metal nanoparticles [emphasis added] in synergistic way to stimulate interest in both photochemistry and nanochemistry and to show the relevance and potentialities of the latter. In Figure 1, it has been demonstrated that color of the solution containing Ag nanoparticles changes after chemiluminescence “catalytic” reaction and the caption indicates the “dissolution of silver particles to colorless solution”. This is due to the oxidation of Ag nanoparticles to silver ions during this process, as suggested in Reaction 2. It has also been mentioned by the author (ref 1, p 697): But in the case discussed here, the emission enhancement is more probably due to catalytic surface effects and could be ascribed to an interaction of silver nanoparticles with the reactants and with the intermediates (eqs 1−4). Silver nanoparticles can catalyze the decomposition of hydrogen peroxide into reactive species such as the hydroxyl radical and superoxide anion, which in turn react with luminol to give the light emission.41 One question that could be raised is “What is a catalyst”? Additionally, one could ask whether Ag nanoparticles could be considered as a catalyst in this reported study.1 The fundamental definition of a catalyst is that it should not be consumed in a reaction. Umland offers this definition: “A material that makes a reaction takes place faster without being used up in the reaction is called a catalyst.”2 In fact, chemistry textbooks and online reference materials describe a catalyst in a similar way. Considering some of the statements provided in the article of interest,1 it provides misleading information to the readers, in particular students and future scientists. References 21 and 41 quoted in the article1 clearly show that the nanoparticles are not consumed by the reaction. In ref 41, they are regenerated after being consumed in one of the reaction steps. The following correction note may rectify the error.
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© XXXX American Chemical Society and Division of Chemical Education, Inc.
The aim of this demonstration is to combine the appealing character of chemiluminescent reactions with the emission enhancement properties displayed by noble metal nanoparticles in asynergistic way to stimulate interest in both photochemistry and nanochemistry and to show the relevance and potentialities of the latter. In the Conclusions Section, we propose this text: This demonstration is suited to introduce and illustrate, both at undergraduate and graduate levels, highly relevant topics, such as redox reactions, photochemistry, materials chemistry, and nanotechnology.
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AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. Notes
The authors declare no competing financial interest.
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REFERENCES
(1) Panzarasa, G. Shining Light on Nanochemistry Using Silver Nanoparticle-Enhanced Luminol Chemiluminescence. J. Chem. Educ. 2014, 91 (5), 696−700. (2) Umland, J. B. General Chemistry, 1st ed.; West Publishing Company: St. Paul, MN, 1993.
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DOI: 10.1021/acs.jchemed.5b00590 J. Chem. Educ. XXXX, XXX, XXX−XXX
