BODY CENTERED CUBIC MAGNESIUM NIOBIUM HYDRIDE WITH FACILE ROOM TEMPERATURE ABSORPTION AND FOUR WEIGHT PERCENT REVERSIBLE CAPACITY

摘要

Hydrogen storage in metal hydrides provides the advantage of highernvolumetric density over the storage of molecular hydrogen in gaseousnand liquid state. Magnesium hydride (MgH2), which has highngravimetrical capacity of 7.6 weight % hydrogen and low cost, isnconsidered a promising material. However the hydrides’s highnthermodynamic stability (approximately -77 kJ/mol H2), necessitatesnoperating temperatures above 300 °C at 1 atmospheric hydrogenndesorption pressure. This is far from meeting the practical operationalnrequirements for an automotive PEM fuel cell. Many efforts arendirected toward modifying the thermodynamics of Mg-H system.nThere have been some promising studies where researchers inducednthermodynamic destabilization of MgH2 via a new application of thenclassic rule of reverse stability [1], or by utilizing nanolayerednstructures to achieve elastic clamping [2], interfacial intermetallicnformation [3], or increased interface energy [4,5].