Quasi‐One‐Dimensional Behaviour of Hydrogen in H0.35MoO3 and H0.33WO3 as Revealed by Proton NMR

Abstract

AbstractThe 1H NMR has been studied in the hydrogen bronzes H0.35MoO3 and H0.33WO3 prepared by galvanostatic cathodic reduction. Both systems reveal an extreme anisotropy of the hydrogen mobility due to quasi‐one‐dimensional behaviour. – In H0.35MoO3 the temperature dependent 1H wideline data give strong evidence that hydrogen is clustered in quasi‐one‐dimensional channels. Analysis of the temperature dependence of the second moment M2, the transverse relaxation time T2, and the spin‐lattice relaxation time T1 yields essentially the same valueEA = 30 kJ/mol for the activation energy of the translational motion of hydrogen within the channels. In H0.33WO3 evidence for the quasi‐one‐dimensional behaviour is provided by the frequency dependence of T1 and the marked non‐exponential recovery of the nuclear magnetization in the vicinity of the T1 minimum. The activation energy for the translational motion is EA = 3.6 kJ/mol only, indicating high mobility of hydrogen in this bronze.