Evidence of Radical Intermediate Generated in the Electrochemical Oxidation of Iodide

Authors

  • Ashantha Fernando
  • Suman Parajuli
  • Krishna K. Barakoti
  • Wujian Miao The University of Southern Mississippi Hattiesburg, Mississippi, 39406, USA.
  • Mario A Alpuche Aviles University of Nevada, Reno http://orcid.org/0000-0003-2615-4115

DOI:

https://doi.org/10.29356/jmcs.v63i3.529

Keywords:

Inner sphere, iodide oxidation, dye-sensitized solar cell, two electron oxidation

Abstract

We present evidence of the generation of radical ion formation during the oxidation of iodide on a fluorine doped tin oxide (FTO) electrode in acetonitrile. The cyclic voltammograms for the oxidation of iodide and triiodide on FTO are significantly different as in the case of the oxidation of Pt electrode.  These differences are assigned to kinetic differences on the FTO surface that require significant over potentials to drive the oxidation of iodide and triiodide. We propose that at the highly positive potentials the iodine radical intermediate, I·, becomes thermodynamically stable at FTO. The radical nature of the intermediate was verified by the formation of radicals of the usual traps of 5,5-dimethyl-1-pyrroline N-oxide (DMPO) and 2,2,5,5 tetramethyl-1-pyrroline N-oxide (TMPO) when these were added to an electrolyzed solution. Irradiation of an iodine solution causes the homolytic cleavage of I2 and yields the same radical intermediate with TMPO as in the electrolysis experiment. Similar results were obtained from the electrolysis of bromide solutions upon addition of TMPO. Short term electrolysis (< 1 h) gives triiodide as a final product while long-term electrolysis (> 17 h) yields additional byproducts. Byproducts were determined to be organoiodines by gas chromatography-mass spectrometry (GC-MS). Overall, our results are consistent with iodine atoms reacting with the electrolyte during electrolysis at the FTO electrode and with a sequential two-electron transfer process.

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Author Biographies

Wujian Miao, The University of Southern Mississippi Hattiesburg, Mississippi, 39406, USA.

 Professor

Department of Chemistry and Biochemistry

Mario A Alpuche Aviles, University of Nevada, Reno

Associate Professor

Department of Chemistry

References

Evans, D. H. Chem. Rev. 2008, 108, 2113-2144 DOI: 10.1021/cr068066l.

Chang, J.; Bard, A. J. J. Am. Chem. Soc. 2013, 136, 311-320 DOI: 10.1021/ja409958a.

Bard, A. J.; Faulkner, L. R. Electrochemical Methods, Fundamentals and Applications; John Wiley and Sons, 2001, p 670.

Gileadi, E. J. Electroanal. Chem. 2002, 532, 181.

Khoshtariya, D. E.; Dolidze, T. D.; Zusman, L. D.; Lindbergh, G.; Glaser, J. Inorg. Chem. 2002, 41, 1728-1738 DOI: 10.1021/ic0100525.

Downard, A. J.; Bond, A. M.; Clayton, A. J.; Hanton, L. R.; McMorran, D. A. Inorg. Chem. 1996, 35, 7684-7690 DOI: 10.1021/ic960642g.

Liu, H.; Kuznetsov, A. M.; Masliy, A. N.; Ferguson, J. F.; Korshin, G. V. Environ. Sci. Technol. 2011, 46, 1430-1438 DOI: 10.1021/es203084n.

Savéant, J. M. Elements of Molecular and Biomolecular Electrochemistry; Wiley-Interscience: Hoboken, New Jersey, 2006, p 203.

Evans, D. H. Chem. Rev. 1998, 52, 194-197 DOI: 10.1021/cr068066l.

Gregg, B. A.; Pichot, F.; Ferrere, S.; Fields, C. L. J. Phys. Chem. B 2001, 105, 1422-1429 DOI: 10.1021/jp003000u.

Liu, Y.; Jennings, J. R.; Huang, Y.; Wang, Q.; Zakeeruddin, S. M.; Gra?tzel, M. J. Phys. Chem. C 2011, 115, 18847-18855 DOI: 10.1021/jp204519s.

Li, D.; Li, H.; Luo, Y.; Li, K.; Meng, Q.; Armand, M.; Chen, L. Adv. Funct. Mater. 2010, 20, 3358-3365 DOI: 10.1002/adfm.201000150.

Lee, J.; Lee, C.; Lee, Y.; Cho, K.; Choi, J.; Park, J.-K. J. Solid State Electrochem. 2012, 16, 657-663 DOI: 10.1007/s10008-011-1405-9.

Tian, H.; Sun, L. J. Mater. Chem. 2011, 21, 10592-10601 DOI: 10.1039/c1jm10598a.

Hattori, S.; Wada, Y.; Yanagida, S.; Fukuzumi, S. J. Am. Chem. Soc. 2005, 127, 9648-9654 DOI: 10.1021/ja0506814.

Hagfeldt, A.; Grätzel, M. Acc. Chem. Res. 2000, 33, 269-277 DOI: 10.1021/ar980112j.

Ardo, S.; Meyer, G. J. Chem. Soc. Rev. 2009, 38, 115-164 DOI: 10.1039/b804321n.

Gardner, J. M.; Abrahamsson, M.; Farnum, B. H.; Meyer, G. J. J. Am. Chem. Soc. 2009, 131, 16206-16214 DOI: 10.1021/ja905021c.

Gardner, J. M.; Giaimuccio, J. M.; Meyer, G. J. J. Am. Chem. Soc. 2008, 130, 17252-17253 DOI: 10.1021/ja807703m.

Rowley, J.; Meyer, G. J. J. Phys. Chem. C 2009, 113, 18444-18447 DOI: 10.1021/jp907265x.

Rowley, J. G.; Farnum, B. H.; Ardo, S.; Meyer, G. J. J. Phys. Chem. Lett. 2010, 1, 3132-3140 DOI: 10.1021/jz101311d.

Popov, A. I.; Geske, D. H. J. Am. Chem. Soc. 1958, 80, 1340-1352 DOI: 10.1021/ja01539a018.

Macagno, V. A.; Giordano, M. C.; Arvía, A. J. Electrochim. Acta 1969, 14, 335-357 DOI: http://dx.doi.org/10.1016/0013-4686(69)85005-X.

Nakata, R.; Okazaki, S.; Fujinaga, T. J. Electroanal. Chem. 1981, 125, 413-420 DOI: http://dx.doi.org/10.1016/S0022-0728(81)80358-0.

Rogers, E. I.; Streeter, I.; Aldous, L.; Hardacre, C.; Compton, R. G. J. Phys. Chem. C 2008, 112, 10976-10981 DOI: 10.1021/jp802934y.

Nelson, I. V.; Iwamoto, R. T. J. Electroanal. Chem. 1964, 7, 218-221 DOI: http://dx.doi.org/10.1016/0022-0728(64)80015-2.

Bourdillon, C.; Demaille, C.; Moiroux, J.; Saveant, J.-M. J. Am. Chem. Soc. 1995, 117, 11499-11506 DOI: 10.1021/ja00151a013.

Eberson, L. J. Chem. Soc., Perkin Trans. 2 1994, 171-176 DOI: 10.1039/p29940000171.

Electron paramagnetic resonance: A practicioner's toolkit; John Wiley and Sons, Inc.: Hoboken, New Jersey, 2009.

Duling, D. R. Journal of Magnetic Resonance, Series B 1994, 104, 105-110 DOI: https://doi.org/10.1006/jmrb.1994.1062.

Wang, Q.; Rodríguez-López, J.; Bard, A. J. J. Am. Chem. Soc. 2009, 131, 17046-17047 DOI: 10.1021/ja907626t.

Frontana-Uribe, B. A.; Little, R. D.; Ibanez, J. G.; Palma, A.; Vasquez-Medrano, R. Green Chem. 2010, 12, 2099-2119 DOI: 10.1039/C0GC00382D.

Yan, M.; Kawamata, Y.; Baran, P. S. Chem. Rev. 2017, 117, 13230-13319 DOI: 10.1021/acs.chemrev.7b00397.

Ibanez, J. G.; Frontana-Uribe, B. A.; Vasquez-Medrano, R. J. Mex. Chem. Soc. 2016, 60, 247-260.

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Published

2019-10-17