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Activation of OER catalysts based on binuclear ruthenium complexes by hydrogen bonding groups

Grant number: 18/04523-1
Support type:Scholarships in Brazil - Post-Doctorate
Effective date (Start): July 01, 2018
Effective date (End): July 31, 2020
Field of knowledge:Physical Sciences and Mathematics - Chemistry
Principal Investigator:Koiti Araki
Grantee:Kalil Cristhian Figueiredo Toledo
Home Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Associated research grant:13/24725-4 - Supramolecular chemistry and nanotechnology, AP.TEM

Abstract

The sustainable production of clean, easy-to-store and carbon-free fuels that can meet the needs of future generations is one of the most important scientific challenges of the 21st century. The conversion of solar energy into electricity and especially in chemical energy using photoelectrochemical cells and artificial photosynthetic systems, particularly the photodecomposition of water in H2 and O2, is a possible goal. In this context, the Oxygen Evolution Reaction (OER) is a tetra-electronic and tetraprotonic reaction that is limiting the efficiency of fuel cells and solar fuel production still. In fact, catalysts that can meet the needs for stability and efficiency have not yet been found, such that innovative strategies need to be developed to improve the understanding of the reaction mechanism, thus making it possible to reduce the high overpotential associated with O2 formation, thus making possible the realization of artificial photosynthetic systems and the storage of solar energy as high energy chemicals.Among the several materials, ruthenium complexes are promising alternatives as OER catalysts. In recent years, mononuclear complexes have been explored intensively, but it has been shown that even in these cases the reaction mechanism involves the formation of a binuclear activated complex. Thus, in this project we focused in the preparation and study of binuclear ruthenium complexes derived from the 2,6-bis(2-pyridyl)benzodiimidazole ligand, whose structures were adjusted to tune the interaction of a water molecule with the two active sites, through the interaction with hydrogen bonding groups such as -OH and -CN, strategically positioned in between the ruthenium complexes, to facilitate the formation of the I2M activated complex and increase the catalytic efficiency, while exploiting the susceptibility of the bridging ligand to PCET reactions to decrease the potential for formation of the catalytically active high valence species. Finally, the catalysts will be connected with materials capable of favoring photoinduced charge separation reactions such as TiO2 semiconductor oxide films, or photosensitizers derived from the [Ru(bpy)3]2+ complex in order to realize photosynthetic systems for solar fuel production. (AU)

Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
SILVA, JOSE LUIS; UNGER, ISAAK; MATIAS, TIAGO ARAUJO; FRANCO, LEANDRO REZENDE; DAMAS, GIANE; COSTA, LUCIANO T.; TOLEDO, KALIL C. F.; ROCHA, TULIO C. R.; DE BRITO, ARNALDO NAVES; SAAK, CLARA-MAGDALENA; COUTINHO, KALINE; ARAKI, KOITI; BJORNEHOLM, OLLE; BRENA, BARBARA; ARAUJO, C. MOYSES. X-ray Photoelectron Fingerprints of High-Valence Ruthenium-Oxo Complexes along the Oxidation Reaction Pathway in an Aqueous Environment. Journal of Physical Chemistry Letters, v. 10, n. 24, p. 7636-7643, DEC 19 2019. Web of Science Citations: 0.
WATER OXIDATION CATALYSTS. Web of Science Citations: 1.

Please report errors in scientific publications list by writing to: cdi@fapesp.br.