Hydrogen in molybdenum and cobalt sulfide catalysts - A neutron compton scattering study on the ISIS electronvolt spectrometer

The mean kinetic energy of chemisorbed hydrogen in molybdenum and cobalt sulfide catalysts has been measured by Compton neutron scattering on the electronvolt spectrometer (eVS) at the Rutherford Appleton Laboratory ISIS facility. Assuming an isotropic harmonic oscillator, the fundamental wavenumbers of vibrations associated with chemisorbed hydrogen are 1430 +/- 34 cm(-1) for MoS2 and 1392 +/- 26 cm(-1) for CoMoS2; there was no hydrogen peak in the eVS spectrum of Co9S8. The frequencies are closer to the mean values expected for H-S stretching and bending vibrations (ca. 1300 cm(-1)) than for H-Mo (ca. 1100 cm(-1)); the chemisorbed hydrogen observed by eVS is evidently bound to sulfur.