THE CONFINEMENT OF HYDROGEN IN LANI5 BY POISONING OF THE HYDRIDE SURFACE

Surface treatment with CO gas was found to contribute to the confinement of hydrogen in hydrogenated LaNi5. The confinement of hydrogen was enhanced by extension of the CO treatment time and by lowering the temperature at which the sample stood in air. Fourier transform IR spectra suggested that CO molecules chemisorbed on the surface of precipitated Ni which is considered to play the role of recombination center of hydrogen atoms. Since the pathway for hydrogen desorption is sealed by chemisorbed CO molecules, hydrogen appears to be confined in LaNi5. It was found that one chemisorbed CO molecule can confine ca. 10(4) molecules of hydrogen when the average diameter of LaNi, particles is about 3.6 mu m.