Effect of electrolyte properties on the electro-oxidation of alcohols on platinum

• Grant number: 22/08723-0
• Support Opportunities: Regular Research Grants
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
• Agreement: DAAD
• Principal Investigator: Hamilton Brandão Varela de Albuquerque
• Grantee: Hamilton Brandão Varela de Albuquerque
• Principal researcher abroad: Yujin Tong
• Institution abroad: University of Duisburg-Essen, Germany
• Host Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated researchers: André Henrique Baraldi Dourado ; Fabio Henrique Barros de Lima ; Germano Tremiliosi Filho
• Associated research grant: 20/15230-5 - Research Centre for Greenhouse Gas Innovation - RCG2I, AP.PCPE

Abstract

The ecological challenges currently facing humanity threaten not only individual growth projections, but also their ability to survive in the foreseeable future. Such alarming prospect has been stimulating a noticeable movement within the academic circles towards favouring more sustainable-oriented research projects, which usually translates into attempts to deeper the understanding and, ultimately, improve economically key chemical processes. Among them, one of particular interest is the electrocatalytic reform of biomass-based organic molecules; since they can be used as an ecologically friendly way to attain electrical energy (e.g., direct ethanol fuel cells) and valuable industrial feedstock compounds (e.g., ethylene oxide). However, in order for both of those options to truly display neutral/negative carbon footprints, the electrochemical cells configuration and experimental conditions used should hinder the complete oxidation of the given reactants to CO2 - meaning that a tight control over the product selectivity is necessary. Such challenge is usually addressed through the modulation of the bulk and/or interfacial properties of the catalytic substrate employed. However, despite their usefulness, there are very few studies in which these two approaches have been applied simultaneously and, at the time, there are no satisfactory explanations to the exact nature of the dependence between the selectivity of the products obtained and the energetic efficiency of the electrochemical reforming processes with the type of reaction medium used. Considering that, the objective of this bilateral project between Brazil and Germany is to investigate possible significant effects on the electro-oxidation mechanisms of small organic molecules such as ethanol and glycerol on Pt electrodes. The effects may arise from (i) the polarity of the medium; (ii) the interfacial mass diffusion and pH gradient and; (iii) the adsorption competition between products, intermediates and ions on the catalyst surface. In order to address such propositions, ethanol and glycerol solutions with different cationic (Li+, Na+, K+, Ca2+ and Mg2+) and anionic (Cl-, ClO4-, SO42- and H2PO4-/HPO42-) compositions were chosen as model systems to be studied on low-index single-crystal platinum electrodes by coupling electrochemical methods with analytical, spectroscopic and computational ones. This project will combine the complementary expertise of the two groups in the field of nonlinear spectroscopy (University of Duisburg-Essen, UDE) and electrochemistry (University of São Paulo, USP). Finally, the balance between young and senior researchers involved in the exchange missions on both sides has been designed to maximize the exchange of practical experience and theoretical knowledge throughout the duration of the proposed collaboration and will be fruitful long after this initial stage. (AU)