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Development, validation and application in mechanistic, structural and electronic proprieties of metal complexes using microjet XPS spectroelectrochemical cells

Grant number: 19/27046-7
Support type:Scholarships abroad - Research Internship - Post-doctor
Effective date (Start): June 01, 2020
Effective date (End): May 31, 2021
Field of knowledge:Physical Sciences and Mathematics - Chemistry
Principal Investigator:Koiti Araki
Grantee:Kalil Cristhian Figueiredo Toledo
Supervisor abroad: Olle Bjorneholm
Home Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Local de pesquisa : Uppsala University (UU), Sweden  
Associated to the scholarship:18/04523-1 - Activation of OER catalysts based on binuclear ruthenium complexes by hydrogen bonding groups, BP.PD

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. Accordingly, systematic studies of the activation process as well as the electrocatalytic properties of transition metal complexes are fundamental. However, among the few techniques proved to be useful in this regard is the X-ray Photoelectron Spectroscopy (XPS) technique especially when associated with synchrotron radiation sources. Materials that have a high potential for use as a probe are compounds based on [Ru(bpy)2(py)(OH2)]2+ whereas relevant intermediate species can be generated by oxidation and characterized by liquid microjet XPS using synchrotron sources under more realistic physicochemical conditions. The liquid microjet XPS technique allows the investigation of the liquid/gas interface and the electronic structure of solvated molecular systems in two different chemical environments since it is an element specific high-resolution technique, sensitive to the oxidation state and the bonding presenting two extremely important advantages for the study of electrocatalysts. Firstly, radiation damage can be avoided even in the case of fragile molecular compounds and secondly, the sample surface remains free of contamination due to continuous renewal. So the main propose of these work is the development of a new microjet spectroelectrochemistry cell, validate the method using simple model complexes by generating electrochemically in flux, in situ, the ruthenium complex species in different oxidation states which will then be studied by XPS And after this, the spectroelectrochemical flow cell will be used to study the reaction mechanism of new OER ruthenium binuclear electrocatalysts and comparing their efficiencies with those already obtained in literature.