Non-isothermal hydrogen desorption from β-UH3: Kinetics and mechanism

Non-isothermal hydrogen desorption kinetics from β-UH3 powder was investigated by means of temperature programmed desorption - mass spectrometry (TPD-MS). The hydride phase of the synthesized powder was determined by X-ray diffraction (XRD); particles size and morphology were characterized by scanning electron microscopy (SEM). The thermal decomposition (dehydrogenation) of β-UH3 is found to follow a zero-order kinetics with an activation energy of 104 kJ/(mol H2). By accounting for the observed kinetics and comparing the activation energy against reported density functional theory (DFT) values, a surface controlled mechanism, limited by surface recombination of hydrogen atoms is proposed.