The state of absorbed hydrogen in the structure of reduced copper chromite from the vibration spectra

Physical Chemistry Chemical Physics Pub Date: 2009-05-13 DOI: 10.1039/B821381J

Abstract

The reduction of copper chromite, CuCr2O4, is followed by means of thermogravimetric analysis. The reduced state is studied by means of FT IR spectroscopy, Raman spectroscopy and inelastic neutron scattering. The reduction of copper occurs in two stages: absorption of hydrogen at 250–400 °C and dehydration of the reduced state at above 450 °C. The measured vibrational spectra prove that a considerable amount of hydrogen is absorbed by the oxide structure with absorbed protons stabilized in OH and HOH-groups (geminal protons). Three groups of vibration bands are observed in the INS spectra, which can be assigned to stretching, bending and libration vibrations. An increase in the reduction temperature of copper chromite results in softening of the stretching and hardening of the bending vibrations, what can be related to the strengthening of hydrogen bonding.

Graphical abstract: The state of absorbed hydrogen in the structure of reduced copper chromite from the vibration spectra
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