Catalysis mechanisms in MgH2-based nanocomposites used for hydrogen storage

• Grant number: 12/18048-7
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Effective date (Start): January 01, 2013
• Effective date (End): July 31, 2014
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
• Principal Investigator: Walter José Botta Filho
• Grantee: Ricardo Floriano
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

In spite of its high desorption temperature and slow kinetics, MgH2 is still considered a good candidate (between the reversible hydrides) for hydrogen storage applications due its high hydrogen storage reversible capacity (7.6 wt. %), low density and low cost. Great improvements were reported for the MgH2 such as, decrease of desorption temperature; very fast H-sorption kinetics; by combining of a nanostructured material produced by high energy ball milling (HEBM) and the doping with selective additives/ catalyst (X). However, there is no clearly understanding or agreement in the literature about the role of the additives in the Mg matrix which is responsible for potentialize the improvements on the hydrogen storage properties. Recently, consolidate industrially techniques involving severe plastic deformation (SPD) have been explored for activation and processing of Mg-based materials and very good hydrogen storage properties were reported. In the doctorate candidate thesis, MgH2+X nanocomposites were processed by SPD techniques and excellent hydrogen storage properties close to materials processed by HEBM were observed, confirming the beneficial action of additives on MgH2 processed by SPD. In this project, we intend to investigate the responsible catalysis mechanisms for the improvements on the hydrogen storage properties in Mg + X and MgH2 + X (X = FeF3 e Nb2O5) nanocomposites processed by HEBM and SPD in different situations: i) verify the additives influence on the desorption/absorption kinetics; ii) and in the activation process of Mg + X processed by SPD; iii) study the microstructural evolution from the nanocomposites under cycling. Advanced characterization techniques such as transmission electron microscopy and high-resolution X-ray diffraction will be employed.