Production of Volatile Species during the Oscillatory Electro-oxidation of Small Organic Molecules

Author(s)

Delmonde, M. V. F. ^[1] ; Nascimento, M. A. ^[1] ; Nagao, R. ^[1] ; Cantane, D. A. ^[1] ; Lima, F. H. B. ^[1] ; Varela, H. ^{[1, 2]}

Affiliation

^[1] Univ Sao Paulo, Inst Chem Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil

^[2] Max Planck Gesell, Fritz Haber Inst, Dept Phys Chem, D-14195 Berlin - Germany

• Document type: Journal article
• Source: Journal of Physical Chemistry C; v. 118, n. 31, p. 17699-17709, AUG 7 2014.
• Web of Science Citations: 14

Abstract

The study of complex reaction under oscillatory conditions has been proven to be useful in uncovering features that are hidden under close to equilibrium regime. In particular, for the electro-oxidation of small organic molecules on platinum and platinum-based surfaces, such investigations have provided valuable mechanistic information, otherwise unavailable under nonoscillatory conditions. We present here the dynamics of production of volatile species along the oscillatory electro-oxidation of formic acid, methanol, and ethanol on platinum, as measured by online differential electrochemical mass spectrometry (DEMS). Besides the presentation of previously unreported DEMS results on the oscillatory dynamics of such systems, we introduce the use of multivariate linear regression to compare the estimated total faradaic current with the one comprising the production of volatile species, namely: carbon dioxide for formic acid, carbon dioxide and methylformate for methanol, and carbon dioxide and acetaldehyde for ethanol. The introduced analysis provided the best combination of the DEMS ion currents to represent the total faradaic current, or, equivalently, the maximum possible faradaic contribution of the volatile products for the global current. The mismatch between estimated total current and the one obtained by the best combination of partial currents of volatile products was found to be small for formic acid, 4 and 5 times bigger for ethanol and methanol, respectively, evidencing the increasing role played by partially oxidized, soluble species in each case. These results were discussed in connection with the mechanistic aspects of each system. Moreover, we have defined some descriptors to account for the production of volatile species, and discussed dynamics in terms of sample and populational covariances. (AU)

• FAPESP's process: 09/07629-6 - Electrocatalysis IV: fundamental and applied aspects of electrocatalytic processes, bio-electrocatalysis and kinetic instabilities
• Grantee: Edson Antonio Ticianelli
• Support Opportunities: Program for Research on Bioenergy (BIOEN) - Thematic Grants
• FAPESP's process: 12/24152-1 - Complex kinetics in electrochemical systems: mechanisms, stoichiometric network analysis and numerical simulations
• Grantee: Hamilton Brandão Varela de Albuquerque
• Support Opportunities: Scholarships abroad - Research
• FAPESP's process: 09/11073-3 - Investigation of the mechanism of ethanol electro-oxidation on metallic nanoparticles.
• Grantee: Daniel Augusto Cantane
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 12/24368-4 - Theoretical study of spatio-temporal behavior in electrochemical systems
• Grantee: Melke Augusto do Nascimento
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• FAPESP's process: 11/10982-0 - Spatio-temporal patterns in electrocatalysis: experiments, modeling and numerical simulations
• Grantee: Melke Augusto do Nascimento
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 09/00153-6 - Spatio-temporal self-organization in electrocatalysis
• Grantee: Raphael Nagao de Sousa
• Support Opportunities: Scholarships in Brazil - Doctorate