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ELECTROCHEMICAL AND MATERIAL CHACTERIZATION OF HYBRID SP2/SP3 CARBON POWDERS FOR USE IN ELECTROCHEMICAL POWER SOURCES

Grant number: 19/10772-7
Support type:Scholarships abroad - Research Internship - Scientific Initiation
Effective date (Start): August 01, 2019
Effective date (End): November 30, 2019
Field of knowledge:Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
Principal Investigator:Nerilso Bocchi
Grantee:Samuel Henrique Mattoso
Supervisor abroad: Greg Michael Swain
Home Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
Local de pesquisa : Michigan State University (MSU), United States  
Associated to the scholarship:18/19759-0 - Study of composites of MnO2 and activated carbon for use as electrode material of hybrid supercapacitors, BP.IC

Abstract

Proton-exchange membrane fuel cells (PEMFC's) are promising candidates for thegreen conversion of hydrogen into electrical energy. A considerable problempreventing the large scale applications of PEMFC's is the inadequate durability of thematerial components, such as the degradation of the supported electrocatalyst layer.Carbon black (CB) is commonly used as the carbon support, however its stability islimiting for long term PEMFC use. CB in the cathode is oxidized in the start and stopcycling of the PEMFC, detaching Pt nanoparticles and promoting agglomerations,which leads to performance loss. This degradation is due to the aggressive conditionsto which the carbon is exposed, such as high water content, low pH, high potential (1.4V vs RHE) and high oxygen concentration. Greg Swain's group at Michigan StateUniversity is proposing a new approach to solve the cathode oxidation problem inPEMFC's. This strategy involves the preparation, characterization and electrochemicalperformance of conducting diamond power. High surface area materials are beingprepared by forming a layer of boron-doped ultrananocrystalline diamond (B-UNCD)over the surface of various substrate powders. Conducting diamond is highly corrosionresistant at the open circuit voltage of a PEMFC (ca. 1.0 V) and at potentials that areeven more positive. Therefore, it is expected that the corrosion resistance anddurability of prepared diamond powders will be much superior that of conventional sp 2carbon support materials, such as CB. Within this context, the proposed projectintends to characterize hybrid sp 2 /sp 3 materials through various techniques. Thetechniques that will be used are X-ray diffraction (XRD), thermogravimetric analysis(TGA), Raman spectroscopy, BET gas adsorption, scanning electron microscopy (SEM),transmission electron microscopy (TEM) and electron diffraction (ED). These analyseswill enable the distinction of sp 2 versus and sp 3 bonded carbon domains and also willpossibilitate a correlation to be made between the micro and nanoscale structure ofthe carbon and the observed electrochemical properties. Additionally, hybriddiamond/nanographene for application in supercapacitors powders are being made, inwhich B-UNCD coating is formed over sp 2 /sp 3 carbon powders. If time is available,initial electrochemical testing of these materials will also be performed.