Hydrogen sorption in orthorhombic Mg hydride at ultra-low temperature

摘要: Abstract Mg can store up to ∼7 wt.% hydrogen and has great potential as light-weight low cost storage materials. However sorption in typically requires ∼573 K, whereas the target operation temperature of fuel cells automobiles is ∼373 K or less. Here we demonstrate that stress-induced orthorhombic hydride (O-MgH2) thermodynamically destabilized at ∼ 373 K lower. Such drastic destabilization arises from large tensile stress single layer O-MgH2 bonded rigid substrate, compressive due volume change incompatibility Mg/Nb multilayers. Hydrogen (H2) desorption occurred at room 10 nm/O-NbH 10 nm Ab initio calculations show constraints imposed by thin-film environment significantly reduce formation enthalpy, verifying experimental observations. These studies provide key insight on mechanisms destabilize other type metal hydrides.