– research in the field of hydrogen energy technologies:
– synthesis of hydrogen separation membranes and analysis of their properties;
– synthesis hydrogen production using water reactions with metals and nanoparticles of their alloys;
– synthesis and analysis of properties of metals and their alloy hydrides designed for hydrogen storage;
– synthesis of hydrogen fuel cell elements anodes/electrolytes/cathodes applying physical vapour deposition methods;
– analysis of materials properties used for NiMH battery electrodes.
In 2014 state funded project Synthesis and characterization of Mg-Ti metal hydrides designed for energy storage was completed. Main issues limiting the application of metal alloys are related to hydrogenation/dehydrogenation process. Presently metal alloys intended for hydrogen storage are widely used. They are formed using chemical technologies. During hydrogenation process of the obtained alloys, hydrogen pressure reaches up to 10 MPa, and dehydrogenation occurs at the temperature up to 500 °C.
Figure 1. XPS spectra of in-situ hydrogenated magnesium surface coatings in hydrogen plasma
The main objective of this work is to discover metastable phases of magnesium hydride, destabilized using titanium additives, where a material efficiently adsorbs/desorbs hydrogen. The main originality of the work is to synthesize MgTiH16 thin layer structures by using magnetron sputtering technologies and complex hydrogenation of materials in plasma and high pressure and temperature. It was observed that after hydrogenation by plasma ion implantation, the increase of all crystalline lattice parameters of magnesium – titanium samples is observed, which occurs due to internal stress between the formed coating and quartz substrate. However, even in this way formed films during its hydrogenation maintains crystalline shape. During the process of hydrogenation in hydrogen plasma, metal Mg-Ti films is only saturated with hydrogen, but only a small part of the material is transformed from metal into crystalline hydride phase; therefore, we believe that this model of hydrogenation process is not efficient, forming compounds of magnesium – titanium hydride on quartz substrate. One of the main findings of the work is related to the experimental fact that in the process of plasma hydrogenation of pure Mg, if after the synthesis the sample is not taken out of the vacuum chamber, and the hydrogenation is performed in in situ mode, a significant increase of the amount of obtained crystalline hydride phase is observed (Figure 1). It is probable that the equivalent results would be obtained also in the case of thin Mg-Ti coating using in situ hydrogenation approach.
Figure 2. Students from Kaunas city universities are frequent guests of Center for Hydrogen Energy Technologies
In co-operation with professors and students of the Department of Physics at Vytautas Magnus University (VDU) and the Department of Physics at Kaunas University of Technology (KTU), the established Center for Hydrogen Energy Technologies accumulates equipment necessary for the research, allows teachers at the Department of Physics at Vytautas Magnus University and at the Department of Physics at Kaunas University of Technology use modern educational aids, prepare highly qualified specialists (including all study levels) and develop competitive research. It is equally important that LEI has become a powerful center of attraction for young researchers (Figure 2).
In 2014 the researchers of the Center actively participated in the research of group 32 Hydrogen based energy storage of International Energy Agency Hydrogen Implementation Agreement (IEA HIA) and in the activities of EU COST program MP 1103: Nanostructured materials for solid-state hydrogen storage. In these works, chemical destabilization of metals and their alloy hydrides is carried out by introducing new elements into materials, which form intermediate derivatives during hydride decomposition, thus preventing the system from relaxing to the lowest energy state or form a destabilized hydride during hydrogenation.
Figure 3. Ni clusters obtained on water-soluble substances (a); elemental map (b)
In 2014 the researchers of the Center continued working on the Project Modification of properties of polystyrene foam surface by means of nanocrystalline oxide coatings (NANOPUTPLAST; Agreement No. VP1-3.1-ŠMM-10-V-02-019). During the research, two technologies were developed, and two patent applications were submitted to the Patent Bureau of Lithuania:
1. Synthesis of nanocrystalline clusters on water-soluble substances by means of magnetron sputtering method (Figure 3). Application number LT2014 509;
2. Protection of polymer material surfaces the use of nanocrystalline oxide coatings (Figure 4). Application number LT2014 510.
Figure 4. Nanocrystalline SiO2 coating on the surface of polystyrene foam
In 2014 the researches of the Center published three research articles in journals listed in Web of Science Core Collection in Thomson-Reuters database and presented five papers at the international conferences.