"Synthesis and characterization of new electrocatalysts for hydrogen peroxide electrogeneration"

Abstract

The use of hydrogen peroxide in Advanced Electrochemical Oxidative Processes (AEOPs) is promising for the treatment of persistent organic pollutants. This oxidant can be in situ produced by oxygen reduction reaction (ORR) on Gas Diffusion Electrode (GDE), which has a highly porous structure. This way, it can assure a continues oxygen gas flow and a steady in situ generation of H2O2. However, the production and stability of H2O2 depend on several factors such as cathode properties, cell/reactor electrochemical configuration and operational conditions since, parasitic reactions such as hydrogen evolution, electrochemical reduction of H2O2 at the cathode surface, H2O2 decomposition and the oxidation of this oxidant at the anode can occur.Since carbon has a high overpotential for the hydrogen evolution reaction and low catalytic activity for H2O2 decomposition, it is widely used as catalyst for ORR, although several properties can be improved. Therefore, by changing the carbon source we change the electron transfer number (reaction efficiency) and overpotential (energy consumption) for ORR as well as the hydrophilicity and stability by further modification with quinone, metal phthalocyanine or transition metal oxides.The main proposal of this project is to develop research activities related to the Thematic Research Project - FAPESP: "Study and application of electrochemical technology for the analysis and degradation of endocrine interferents: materials, sensors, processes and scientific dissemination", with the supervision of the project coordinator Prof. Dr. Marcos R. V. Lanza.Of special interest, the carbon has a crucial impact on the selectivity for H2O2 electrogeneration. Initially, the catalytic activity of carbon-based materials such as biomass and carbon nitride will be investigated. Subsequently, these materials will be modified in order to increase their catalytic properties for oxygen reduction to H2O2. Among the modifiers, it will be investigated ferrocene allowing the use of this catalyst in Fenton-like process in both acid and alkaline media. The best catalysts will be used to prepare GDEs, which will be applied in AEOPs to treat wastewater containing endocrine disruptors. During these processes, the kinetics of degradation and mineralization of the organic compounds will be monitored. Furthermore, the intermediates formed will be identified in order to establish the representative mechanisms for each compound, and the toxicity of the degradation byproducts will be investigated.