Direct Liquid Fuel Cells-The Influence of Temperature and Dynamic Instabilities

Author(s)

Nogueira, Jessica A. ^[1] ; Varela, Hamilton ^[1]

Affiliation

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

• Document type: Journal article
• Source: ENERGY & FUELS; v. 34, n. 10, p. 12995-13009, OCT 15 2020.
• Web of Science Citations: 0

Abstract

The interconversion between chemical and electrical energies plays a pivotal role in the challenge for a sustainable future. Proton exchange membrane fuel cells based on the electro-oxidation of hydrogen and reduction of oxygen comprise a relatively mature technology of indisputable relevance. Alternatively, some open questions concerning the use of direct liquid fuel cells (DLFCs) call for further experimental investigations. In this paper, we evaluate the temperature effect on DLFCs under conventional and oscillatory conditions. We studied four molecules: methanol, formic acid, ethanol, and dimethyl ether (DME). The use of identical experimental conditions allowed evaluation of the role of the fuel on DLFC performance, thus providing reference values for future investigations. Under a regular, nonoscillatory regime, we observed for all cases that the overpotential decreases as the temperature increases mainly because water activation on the catalyst surface is facilitated at high temperatures. By mapping the conditions where oscillatory kinetics manifest itself under the galvanostatic mode, only the electro-oxidation of DME did not exhibit potential oscillations. The relationship between oscillatory frequency and temperature during the methanol and formic acid electro-oxidation followed a conventional Arrhenius dependence, whereas with ethanol, there was no straightforward trend, and temperature compensation prevails. The atypical behavior found for ethanol was addressed in terms of its main electrocatalytic poisons: adsorbed CO and acetate. The absence of oscillations during DME electro-oxidation was attributed to its weak interaction with the catalyst surface. (AU)

• FAPESP's process: 15/09295-9 - Dynamic behavior in low-temperature fuel cells based on oxidation of small organic molecules
• Grantee: Jéssica Alves Nogueira
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 17/17644-9 - Stability of electrocatalysts towards the electro-oxidation of organic molecules
• Grantee: Jéssica Alves Nogueira
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• FAPESP's process: 13/16930-7 - Electrocatalysis V: electrocatalytic processes of chemical and electrical energy interconversion
• Grantee: Edson Antonio Ticianelli
• Support Opportunities: Research Projects - Thematic Grants