Inelastic incoherent neutron scattering study of the molecular properties of pure hydrogen peroxide and its water mixtures of different concentration.

We have investigated the spectra of shock-frozen H2O2-H2O mixtures across the full composition range 99.1%-0.0% H2O2. In contrast to literature reports, we find that intermediate compositions (30%-70% H2O2) freeze to a solid solution rather than phase separating, which only occurs on annealing to just below the melting point. We have fully characterised the dihydrate H2O2·2H2O (48.6% H2O2) for the first time and shown that its spectrum can account for the features previously observed on the surface of a Au/TiO2 catalyst.