Identification of the mechanism for the formation of core-shell transition-metal nanoparicles using density functional theory

• Grant number: 12/13934-9
• Support Opportunities: Scholarships in Brazil - Master
• Start date: October 01, 2012
• End date: August 31, 2014
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
• Principal Investigator: Juarez Lopes Ferreira da Silva
• Grantee: Ricardo Kita Nomiyama
• Host Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated research grant: 08/00782-0 - Computational catalysis: hydrogen production from ethanol, AP.JP

Abstract

One of the huge problems for the commercial use of ethanol in fuel cells is the development of catalysts that are: efficient, stable, and low production cost. A typical catalyst is composed of transition metal particles deposited on oxide (CeO2, Al2O3, ZrO2, SiO2, etc.). Pt, Rh, and Pd are among the most investigated systems for understanding the process of ethanol electro-oxidation, however, there are a number of unsolved problems due mainly to the formation of a large number of intermediates, many of which are not identified accurately, can directly affect the performance of the electro-oxidation of ethanol, as well as the high cost of these elements. Therefore, there are several interest to develop new catalysts which can contribute directly to improve the reaction of the ethanol electro-oxidation or even other chemical reactions. In recent years, a great number of experimental studies have suggested that transition metal nanoparticles (NPs) can significantly contribute to solve these problems due to high reactivity observed in NPs compared to macroscopic particles and because of the possibility of combining two or more chemical elements in the same NP. Several studies have been performed using structures called core-shell, in which the core of the particles is composed of an element, while the surface is covered by another element, can directly contribute to reduce the cost of catalysts and/or increase their catalytic ability. For example, the core may be formed by cobalt, copper, etc., while the same is covered by atoms of Pt, Rh, Pd, etc. Despite the large number of previous studies (see below) for NPs with core-shell type structure, there are a large number of open questions: (i) What transition metals can form stable core-shell structures? (ii) What are the mechanisms that determine the stability of core-shell NPs? (iii) What is the magnitude of the change in reactivity of the NPs due to formation of core-shell structures? To contribute to the solution of these problems, in this master's project, the student Ricardo Kita Nomiyama will study the formation, energetic stability, electronic structure, and reactivity of core-shell NPs using first principles methods (density functional theory).

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

NOMIYAMA, Ricardo Kita. Computational study of platinum nanoalloys using density functional theory. 2015. Master's Dissertation - Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD) São Carlos.