Resumen de Ru, co and cu-based catalysts for artificial photosynthesis
Artificial photosynthesis offers a viable alternative to the actual energetic model based mainly in the consumption of fossil fuels. Trying to emulate the photosynthesis process in higher plants, this area of study attempts to use sunlight in order to produce electrons, protons and oxygen from water, with the aim of using the released electrons for producing hydrogen or other useful fuels. Within this context, the use of catalysts usually based in transition metals is necessary to make these two processes viable.
The first chapter contains a brief introduction about the motivation for the research presented in this thesis. The most relevant general mechanistic aspects for water oxidation (WO) as well as proton reduction catalysis are also presented, giving a general view of most relevant catalysts reported to date.
The second chapter is focused in the objectives of this work. The main goal of this PhD thesis is the synthesis and the structural and electrochemical characterization of a series of Ru, Co and Cu-based catalysts and the ulterior study of their reactivity towards water oxidation and/or proton reduction catalysis. The final objective is to fully understand the mechanistic pathways and the factors that affect their catalytic performance for helping in the future rational design of more efficient and robust catalysts.
In the third chapter, the synthesis, characterization and reactivity of a new family of Ru complexes is presented. A series of detailed electrochemical, spectroscopic and kinetic studies allows the identification of new species formed after oxidation of the complexes in aqueous solution that proved to be key for further understanding their catalytic behavior in water oxidation. The fourth chapter presents the synthesis and characterization of a new family of Cu complexes. Their reactivity towards water oxidation has been studied and compared with that of the most relevant Cu-based WO catalysts reported in the literature. Finally, in the fifth chapter we present the deactivation of a CoII/CoIII molecular cluster after application of reductive potentials, giving rise to the formation of CoO or CoO(OH) nanoparticles deposited onto a glassy carbon electrode. The ability of these nanoparticles for reducing protons has been tested, and their catalytic performance discussed on the basis of the nature of the species obtained and their morphology .
In the sixth chapter the most relevant conclusions of this work are discussed. Finally, the last chapter includes an annex containing other works that have been carried out and published during this PhD thesis and that are closely related with the work carried out during the PhD.
