Impact of pH on ethanol electro-oxidation in seawater-like electrolytes: implications for ocean-based mitigation strategies

Author(s)

Ferraz, Thiago V. de B. ; Tremiliosi-Filho, Germano ; Varela, Hamilton

• Document type: Journal article
• Source: Journal of Solid State Electrochemistry; v. N/A, p. 20-pg., 2025-02-08.

Abstract

This study investigates the electro-oxidation of ethanol in seawater-like electrolytes with adjusted pH, exploring its potential for CO2 mitigation strategies. Using a polycrystalline platinum bead as a model catalyst in a conventional three-electrode cell, we demonstrate that pH adjustment significantly influences electrochemical performance, with higher oxidation current densities observed at more alkaline pH values. At pH 12, usable current densities for ethanol oxidation were achieved, attributed to the decreased surface coverage of Cl- ions and increased ethoxy ion concentrations, consistent with observations from similar systems in the literature. However, mass transport limitations emerged at higher potential scan rates, evident from the inversion in peak current densities between pH 13 and pH 14 compared to lower scan rates. Additionally, voltammetric profiles indicated a preference for certain platinum crystallographic faces due to variations in chloride and sulfate binding strength. Notably, potential oscillations, not previously reported under such elevated Cl- concentrations, further support these findings. Tafel analysis in the high potential region (> 1.2 V) revealed that the platinum oxide surface does not become more sensitive to ethanol oxidation with increasing pH. These insights provide an initial understanding of the main opportunities and challenges in studying and applying such systems. (AU)

• FAPESP's process: 20/15230-5 - Research Centre for Greenhouse Gas Innovation - RCG2I
• Grantee: Julio Romano Meneghini
• Support Opportunities: Research Grants - Research Centers in Engineering Program
• FAPESP's process: 14/50279-4 - Brasil Research Centre for Gas Innovation
• Grantee: Julio Romano Meneghini
• Support Opportunities: Research Grants - Research Centers in Engineering Program
• FAPESP's process: 19/22183-6 - Electrocatalysis VI: fundamental and applied aspects of emerging and classical problems in electrochemical energy conversion
• Grantee: Edson Antonio Ticianelli
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 21/13002-8 - Study of the electrooxidation of small organic molecules in saline solutions for the simultaneous valorization of biomass and CO2 mittigation
• Grantee: Thiago Vasconcelos de Barros Ferraz
• Support Opportunities: Scholarships in Brazil - Doctorate