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Metal-support interactions in electrocatalysis: influence of supports containing carbides on the oxygen reduction reaction on PD nanoparticles

Grant number: 18/20780-4
Support type:Scholarships in Brazil - Doctorate
Effective date (Start): April 01, 2019
Effective date (End): February 28, 2021
Field of knowledge:Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
Principal Investigator:Hebe de las Mercedes Villullas
Grantee:Gabriel Martins de Alvarenga
Home Institution: Instituto de Química (IQ). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

Metal-support interactions can modify the electronic properties of a metal, and may considerably modify the speed of reaction steps of the mechanism involving adsorbed species. This project proposes to perform comparative and systematic studies of the effects of alternative supports on the oxygen reduction reaction on Pd nanoparticles in acidic and alkaline media. We propose to study the reduction of oxygen on Pd nanoparticles supported on a carbide (SiC, TiC and WC) and on hybrids carbon-carbide (C-SiC, C-TiC and C-WC) aiming to elucidate the influence of supports on the catalytic activity of Pd. These studies will be carried out comparing the catalytic performance of Pd towards the reduction of oxygen for catalysts prepared with identical Pd nanoparticles, analyzing the effect of different carbides with equal particle size (TiC - 50nm vs. SiC - 50nm; TiC - 200 nm vs. WC - 200nm) and the effects of the particle size of the same carbide (TiC - 50nm vs. TiC - 200nm). Besides characterizing the catalysis by X-Ray Diffraction (XRD and Transmission Electron Microscopy (TEM), studies by X-ray Photoelectron Spectroscopy (XPS) will be carried out to evaluate if metal-support-interactions modify the binding energy of the Pd 3d signal and to determine the fraction of oxidized species. The effects of metal-support interactions on the electronic occupation of Pd 4d band will be investigated by X-ray Absorption Spectroscopy (XAS). The catalytic activity for the oxygen reduction reaction and the stability of the materials will be evaluated by electrochemical techniques (cyclic voltammetry and rotating ring disc electrode). The proposal aims to establish activity-properties correlations and to contribute to the development of Pt-free catalysts for fuel cathodes. (AU)