EMU granted in process 2022/12895-1: Raman spectroscopy system

• Grant number: 24/13932-3
• Support Opportunities: Multi-user Equipment Program
• Start date: December 01, 2024
• End date: November 30, 2031
• Field of knowledge: Engineering - Sanitary Engineering - Water Supply and Wastewater Treatment
• Principal Investigator: Marcos Roberto de Vasconcelos Lanza
• Grantee: Marcos Roberto de Vasconcelos Lanza
• Host Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated research grant: 22/12895-1 - Advanced processes for the degradation of emerging pollutants: catalytic materials, electroanalytical sensors and scientific dissemination, AP.TEM

Abstract

Raman spectroscopy is a vibrational spectroscopic technique that allows fundamental and molecular characterization of both catalysts and catalytic reactions. Raman spectra provide important information about reaction mechanisms, revealing specific information about the structure of the studied catalysts both in the solution and on the surface, as well as the presence of adsorbates and reaction intermediates. More recently, the use of the Raman technique can be used for in situ studies of catalysts in operation by means of spectroelectrochemistry. Thus, it is possible to monitor oxidation states that can be electrochemically altered at an electrode at a given applied potential and the formation of reaction intermediates formed, in which the acquisition of the Raman spectrum in the solution adjacent to the electrode occurs simultaneously. In this way, relationships between reaction mechanisms can be established and the information obtained electrochemically is complemented by optical characterization. A simple approach could be to perform the electrochemical reaction and subsequently perform the optical characterization of the solution or the electrode surface. However, this type of measurement (ex situ) does not provide information regarding the electrochemical reaction taking place. Therefore, it is impossible to optically detect any changes related to the molecules produced and/or consumed during the electrochemical process near the electrode surface. Thus, obtaining this equipment is justified in order to elucidate the mechanisms involved before, during and after the electrochemical reaction of interest, such as the identification of reaction intermediates and even the identification of reaction products. For example, during the study of hydrogen peroxide electrogeneration on the surface of modified or unmodified carbonaceous materials, it is possible to detect the OO and OH stretching vibrations in the H2O H2O2 solution that can be measured using a 532 nm laser. Another example is that in situ Raman spectroelectrochemical characterization is capable of providing evidence of which are the most active sites for hydrogen peroxide production, providing new ideas for the synthesis of new electrode materials for an efficient production of the oxidant. Finally, during and after a hydrogen peroxide electrogeneration reaction, the identification of the structure, reaction intermediates or the definition of reaction products occurring during the electrochemical reaction are examples of the great potential of this hybrid technique. This equipment will be coupled to a Metrohm potentiostat, model PGSTAT-302N, acquired with resources from the completed thematic project (Process 2017/10118-0) and in operation in the GPEA laboratories. (AU)