Protonic species in H1.7MoO3

Abstract

The nature of hydrogen in H1.7MoO3 has been investigated with solid state nuclear magnetic resonance. Samples prepared utilizing wet chemical reduction of MoO3 in zinc and HCl, and dry hydrogen spillover on platinized MoO3 have been characterized by proton NMR with and without strong proton decoupling and magic angle spinning. The results of these experiments indicate that there are at least two types of protons in these ’’hydrogen molybdenum bronzes’’ with the relative amounts depending upon the method of preparation. The major protonic species in both samples exhibit a shielding anisotropy which negates its identification as a hydroxyl proton in a hydrogen bond or as a proton belonging to H2O undergoing rapid rotation at room temperature. The NMR spectra of protons in samples prepared by different methods are, in addition, distinctly different at 90 K. Photoelectron spectroscopy indicates that the molybdenum species in both types of samples are identical to within the resolution of the experiment.