Prussian blue derivatives as smart materials for technological applications

Identifier:  TDX:2646

Handle: https://hdl.handle.net/20.500.11797/TDX2646

Authors:  Rodríguez García, Bárbara

Abstract:
Transition metal hexacyanometallates are an important class of inorganic coordination compounds, isostructural with the original mixed-valence Prussian blue (PB). Their non-stoichiometric nature and chemical variety make of them a versatile type of molecule-based materials. Indeed, a wide range of applications has been described. In this thesis, we explored further applications for Prussian blue analogues, modifying their composition and processing to target several technological issues. First, the catalytic performance of cobalt iron Prussian blue analogues (CoHFe) to promote oxygen evolution reaction in a water splitting was tested. Catalyst nanoparticles were active and efficient in a wide pH range and is stable and functional in the long run even in sea water. Then we incorporate this catalyst in full-cell devices. On one hand, we built and tested a polymer electrolyte membrane (PEM) containing CoHFe as water oxidation electrocatalyst. On the other, we took advantage of CoHFe stability in sea water for the design and construction of a lab scale seawater electrolyzer. We also report our aims to obtain a chiral magnet. Through incorporation of a natural aminoacid (L-proline) in the synthesis of the vanadium-chromium Prussian blue analogues (VHCr), we were able to obtain, and characterize chiral magnets that exhibit spontaneous magnetization at the highest temperatures ever reported, and close to room temperature. Finally, we present our studies for the development of manganese iron Prussian blue analogues (MnHFe) as multimodal contrast agent. These derivatives are potential non-toxic contrast agents nuclear magnetic resonance and optical microscopy (second harmony generation) diagnosis techniques. To expand their multimodal features, we increase their extinction coefficient versus x-ray irradiation by incorporated alkaline metal cations to their structure. We successfully demonstrate that these materials show x-ray attenuation capabilities superior to state-of-the-art commercial tomography contrast agents. In summary, we have demonstrated the versatility of PBAs for multiple applications by modifying building blocks and components. The robustness of the structure, and the multiple redox/composition/processing parameters maintain open unlimited opportunities for potential technological applications.