Issue 36, 2010

Spectroscopic CW-EPR and HYSCORE investigations of Cu2+ and O2 species in copper doped nanoporous calcium aluminate (12CaO·7Al2O3)

Abstract

Continuous wave (CW) and pulse electron paramagnetic resonance in a variant of hyperfine sublevel correlation spectroscopy (HYSCORE) were used for obtaining structural information concerning speciation and local environment of alien Cu2+ and native O2 ions encaged in copper doped nanoporous 12CaO·7Al2O3 (mayenite). The samples were prepared by a solid-state reaction and characterized by means of XRD, SEM, and Raman techniques. X-Band CW-EPR spectra showed that three different Cu2+ species together with paramagnetic extraframework O2 anions were present in the mayenite sample, whereas extraframework OH anions were revealed by Raman spectroscopy. 27Al HYSCORE provided evidence for the interaction of Cu2+ ions with the mayenite framework. Superhyperfine interaction of the Cu2+ ions with proximal (dCuOH = 2.4 Å) and distal (dCuOH = 5.0 Å) OH anions, located in the same and the nearby cage, respectively, was resolved by means of 1H HYSCORE spectra. A different situation held for the encaged O2 radicals found to be sitting on the Ca2+ ions. They exhibited only a weak superhyperfine interaction of 1 MHz with the 27Al3+ framework ions.

Graphical abstract: Spectroscopic CW-EPR and HYSCORE investigations of Cu2+ and O2− species in copper doped nanoporous calcium aluminate (12CaO·7Al2O3)

Supplementary files

Article information

Article type
Paper
Submitted
31 Mar 2010
Accepted
08 Jun 2010
First published
26 Jul 2010

Phys. Chem. Chem. Phys., 2010,12, 10933-10941

Spectroscopic CW-EPR and HYSCORE investigations of Cu2+ and O2 species in copper doped nanoporous calcium aluminate (12CaO·7Al2O3)

S. Maurelli, M. Ruszak, S. Witkowski, P. Pietrzyk, M. Chiesa and Z. Sojka, Phys. Chem. Chem. Phys., 2010, 12, 10933 DOI: 10.1039/C0CP00084A

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