KNOTEK Vítězslav VŠCHT v Praze

Spoluautoři VOJTĚCH Dalibor

There is a general hydrogen conception to overcome unstable production of electric energy from renewable resources, such as wind-power or solar-power plant. This conception consists in generation of hydrogen by using water electrolysis and its storing. However, there is a problem, how to store huge amount of hydrogen in a small volume. The ideal storage system should be able to store much more hydrogen than pressure cylinder, but without necessity of pressure usage which consumes a lot of energy. As a very perspective method seems to store hydrogen in the form of metallic hydrides. For example, magnesium hydride (MgH2) is able to store up to 7.6 wt.% of hydrogen. This volume corresponds approx. to 900 dm3 of hydrogen in one kilogram of MgH2. The drawback of MgH2 is the necessity of using high pressure of gas hydrogen at high temperature for its formation, because of kinetic and thermodynamic reasons. A possibility how to improve thermodynamics and kinetics of MgH2 formation is doping, especially by Ni and other transition metals. In this work, several as-cast ternary Mg-Ni-X alloys (X=transition metal) were hydrided at elevated temperature by electrochemical method. The advantage of this method is the production of hydrogen from water solution and possibility to direct storage of hydrogen in the form of metal hydrides, because a suitable alloy serves as a cathode. Hydrogen concentrations in investigated alloys were measured by glow discharge spectrometer (GDS). The influence of doping transition metals on the ability of Mg-Ni-based alloys to absorb hydrogen was evaluated.

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