Boosting electrochemical H2O2 generation from waste-derived activated carbon using Pd and Pt catalyst modification

• Grant number: 23/04230-2
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: July 24, 2023
• End date: July 23, 2024
• Field of knowledge: Engineering - Sanitary Engineering - Water Supply and Wastewater Treatment
• Principal Investigator: Marcos Roberto de Vasconcelos Lanza
• Grantee: Julio César Lourenço
• Supervisor: Marc Ledendecker
• Host Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Institution abroad: Technical University of Munich, Straubing (TUM), Germany
• Associated to the scholarship: 21/12053-8 - Use of sewage treatment sludge in the synthesis of active carbon modified with nanostructured oxides (Ce, Nb, Ta, and Pd ) and its application in the electrochemical generation of hydrogen peroxide, BP.PD

Abstract

Emerging contaminants are becoming a major problem in modern society, as these products cause a high environmental impact and conventional wastewater treatment plants does not remove these types of pollutants completely. One efficient way to treat contaminants is through an Advanced Oxidation Process (AOP). This process uses a powerful oxidant to break down pollutants. The hydroxyl radical is commonly used for this purpose and can be obtained by reducing H2O2. However, this method requires large amounts of H2O2, which is produced through the environmentally challenging anthraquinone process and has safety and hazard concerns. An alternative is to produce H2O2 electrochemically using gaseous diffusion electrodes (GDEs) to increase oxygen levels. This approach can make it easier to apply AOP technology in sewage treatment plants. These electrodes are usually constructed with commercial amorphous carbon, as this material is suitable for H2O2 generation. Among the most common carbon materials used for these electrodes includes the commercially available Printex 6L (Orion) and Vulcan XC 72R (Cabot). However, their production is unfortunately not environmentally friendly and non-sustainable, as its production is based on the incomplete combustion of heavy petroleum products such as Fluid Catalytic Cracking (FCC) tar, coal tar, or ethylene cracking tar at temperatures as high as 2000°C, generating greenhouse gases and other pollutants. Although amorphous carbon can be obtained from C-rich wastes, its application for electrochemical generation of H2O2 has not been studied yet. This presents an opportunity to investigate the potential of new, sustainable, and cost-effective amorphous carbon for this purpose. While bare carbon does generate a good amount of H2O2 in GDE applications, surface modification can enhance its catalytic activity and reduce energy consumption. This proposal aims to modify activated carbon obtained from solid waste, such as sewage sludge and sugarcane bagasse, with Pd and Pt metals for the electrochemical generation of H2O2. Clearly, one goal is to obtain atomically dispersed Pd and Pt active sites on waste-derived carbons and to evaluate its activity and selectivity towards hydrogen peroxide. The employed modification technique based on incipient wetness impregnation can fine-tune these metals on the carbon support to improve its electrochemical activity toward H2O2 generation. Another objective of this proposal is to assess the catalyst's stability under harsh conditions and implement measures to enhance its overall stability. In order to do so, the catalyst's stability will be observed by potential dependent operando methods to assess its degradation after several cycles of applied potentials, leading to an optimal condition for application oriented long-term applications. The activated carbon obtained from waste materials has already been produced by the candidate. The best modified materials will be brought back to Brazil to be applied in a laboratorial scale plant to test the electrochemical generation of H2O2. The single-atom catalysts dispersed over the material using low-loadings of noble metals is attractive from an economical point-of-view by using lesser amounts of such metals and from an academic point-of-view since it will be a pioneer study on how these modifications will behave on a sustainable and low-cost support. The development of such materials may open a new line of study to develop other types of solid waste-derived materials for electrochemical generation of H2O2. (AU)