Microwave frequency behavior of the EPR copper(II) ion pairs spectrum formed in CuCe oxide

In Situ EPR Study of the Redox Properties of CuO–CeO2 Catalysts for Preferential CO Oxidation (PROX)

“…Oxygen isotope exchange between gas-phase oxygen and the catalyst surface in a temperature range from 393 to 473 K was investigated by multipulse experiments, exposing the freshly calcined and, hence, fully oxidized CuO−CeO 2 materials (10 mg, diluted 1:2 with SiO 2 and packed between two layers of 60 mg of SiO 2 ) at 393 and 473 K to sequences of O 2 /Ar pulses (45% 18 O 2 , 4% 18 O 16 O, 1% 16 O 2 , and 50% Ar) with a separation time of 12 s between individual pulses. SiO 2 as well as the metal sieves were checked to be inactive for oxygen isotope exchange under the reaction conditions applied (393−473 K).…”

“…Electron paramagnetic resonance (EPR), in particular, gives detailed information on the presence of metal ions with unpaired electrons and is hence suitable for systematic mechanistic studies. However, EPR spectra for CuO–CeO 2 systems have so far been reported only for temperatures in the range from 77 K to room temperature. − Cu monomer and dimer signals were identified in the spectra recorded at room temperature. Moreover, the intensity of these signals decreased significantly when the sample was reduced at 573 K and cooled to room temperature .…”

Effect of Mg Addition on the Physical and Catalytic Properties of Cu/CeO2 for NO + CO Reduction

“…Signal A 1, which is contributed by isolated Cu 2? in octahedral sites of ceria with a tetragonal distortion [30][31][32][33], exhibits four-line hyperfine splittings and shows g k = 2.345, A k = 125 G for Cu/CeO 2 , g k = 2.331, A k = 153 G for Cu/CM5 and g k = 2.327, A k = 153 G for [34]. Also, it is found that the intensity increases with the increase of MgO content at the beginning (i.e., Cu/ CM5), but then decreases with further increase of MgO content (i.e., Cu/CM10).…”

“…Therefore, in our case, the catalyst with higher intensity of signal A 1 also shows higher intensity of signal K. Signal A 2 is attributed to isolated Cu 2? localized in surface substitution sites of ceria [33]. It has been reported that ionic mobility stimulated by anion vacancies or high temperature could promote the substitution of Cu 2?…”

Cu- and Ag-Modified Cerium Oxide Catalysts for Methane Oxidation

“…As a result, the reducibility of ceria at low temperatures is enhanced (40,41). Recent reports have shown that the oxidation activity of ceria can be largely enhanced not only by the platinum metals but also by transition metals in general (42)(43)(44). However, the interaction of nanocrystalline ceria with metals and its ensuing higher activity in oxidation reactions is not well understood.…”