Structural, electronic and photochemical properties of cerium-doped zirconium titanate

Ce Doping Boosts the Thermo‐ and Photocatalytic Oxidation of CO at Low Temperature in TiZrO4 Solid Solutions

“…The Ce x ‐ZT powders were investigated by some of us in previous works [ 17a ] and consist of a solid solution of titania and zirconia (ZrTiO 4 ) with the structure of scrutinyite, typical of α‐PbO 2 , where the cerium cations occupy substitutional positions, either in the Ce(III) or Ce(IV) oxidation state. For an increasing amount of ceria, and in particular, at 10% loading, a small amount of pure ZrO 2 phase starts to segregate, setting a limit to the amount of cerium that can be introduced in the samples.…”

“…It has been demonstrated by electron paramagnetic resonance (EPR) studies that the Ce(III)/Ce(IV) redox couple can activate molecular oxygen as superoxide radical anion O 2 •− , making this solid solution a quite interesting material for redox reactions and in particular oxidations. [ 17b ] In the following, we will focus on the characterization of the materials after the decoration with Pd nanoparticles (NPs) and on the study of the resulting catalytic properties.…”

“…Actually, in a previous work it has been demonstrated that Ce(III) cation in zirconium titanate can interact with molecular oxygen and produce (98%) weakly bonded superoxides species, which are known to be key intermediates in the CO oxidation reaction. [ 17b ] On the other hand, the Zr 3d and Ti 2p spectra photoemission spectra do not show any change after the deposition of palladium and the detected amount of reduced species is negligible (Figures S22–S25, Supporting Information). These results are in agreement with previous works on the same materials, which showed that the 4f levels of ceria are lower in energy of both Ti 3d and Zr 4d states, therefore are preferentially populated, determining the selective formation of large amount of Ce(III) species.…”

“…•− Ce 4+ ). [17,29,30] The second one, weaker and partially buried in the previous signal is the evidence of superoxide species adsorbed on the tetravalent ions of the zirconium titanate lattice (O 2…”

“…[16] The doping of ZrTiO 4 with cerium (forming the systems hereafter labeled as Ce x -ZT, where x indicates the molar fraction of Ce) has been recently studied by some of us. [17] It has been demonstrated that cerium cations can be substitutionally introduced in the lattice of the zirconium titanate up to a level of 10 mol%. Interestingly, theoretical calculations and X-ray photoelectron spectroscopy (XPS) data indicated that the empty Ce 4f levels are lower in energy than the Ti 3d and Zr 4d bands, allowing an easy and selective formation of reduced Ce 3+ species.…”