Pr 4f Research Articles

Photoluminescence properties of Pr-doped LaAsO4: An experimental and theoretical study employing density functional theory

Praseodymium doped lanthanum arsenate, denoted as La1-xPrxAsO4, has been synthesized with different concentrations of the dopant (x = 0.5 %; 1 %; 2 %; 3 % and 5 %) via the combustion method and their optoelectronic properties have been investigated. A study of the crystalline structure and size of the compound by XRD confirms that both the pristine LaAsO4 and Pr-doped LaAsO4 are pure and maintain a monoclinic crystal structure, with the crystalline size ranging from 60 to 76 nm. The morphological study of the nanoparticles by SEM analysis reveals that all samples, regardless of the concentration of Pr3+, consist of homogeneously packed and irregularly shaped small particles. The optical studies by absorption and fluorescence spectroscopies highlight the unique optoelectronic characteristics of La1-xPrxAsO4, with absorption predominantly in the UV and blue regions and prominent emission peaks in the visible spectrum, most notably at 610 nm. The optimal luminescence is observed at a 0.5 % Pr3+ doping level, deviating from typical trends as higher concentrations lead to diminished emission intensity and lifetime due to concentration quenching effects. The application of Density Functional Theory (DFT) with GGA + PBE and GGA + PBE + U approximations has effectively elucidated the electronic structure and optical properties of the Pr-doped LaAsO4. The incorporation of Pr's 4f states within the LaAsO4 forbidden band significantly alters the material's electronic landscape, notably reducing the optical band gap from 4.45 eV to 2.299 eV. This modification in the band structure aligns favourably with the dielectric function curves and density of states analyses, corroborating the observed visible light emission in the doped samples.

Spin-orbit coupling of electrons on separate lanthanide atoms of Pr2O2 and its singly charged cation.

Although it plays a critical role in the photophysics and catalysis of lanthanides, spin-orbit coupling of electrons on individual lanthanide atoms in small clusters is not well understood. The major objective of this work is to probe such coupling of the praseodymium (Pr) 4f and 6s electrons in Pr2O2 and Pr2O2+. The approach combines mass-analyzed threshold ionization spectroscopy and spin-orbit multiconfiguration second-order quasi-degenerate perturbation theory. The energies of six ionization transitions are precisely measured; the adiabatic ionization energy of the neutral cluster is 38 045 (5) cm-1. Most of the electronic states involved in these transitions are identified as spin-orbit coupled states consisting of two or more electron spins. The electron configurations of these states are 4f46s2 for the neutral cluster and 4f46s for the singly charged cation, both in planar rhombus-type structures. The spin-orbit splitting due to the coupling of the electrons on the separate Pratoms is on the order of hundreds of wavenumbers.

New insight into the coloration mechanism and synthesis of ultrafine Pr‐ZrSiO4 yellow pigments

AbstractIt is of particular significance to unveil the authentic coloration mechanism of the multivalent praseodymium colored ZrSiO4 yellow pigments for advanced decoration applications. We herein adopted a facile strategy to modulate the fluorine‐assisted zircon crystallization and thereby obtained ultrafine Pr‐ZrSiO4 yellow pigments, which have a remarkably narrow size distribution and average diameters within 250–400 nm. By virtue of some cogent combinative spectra of reflection, absorption, excitation, and emission from three types of elaborately‐designed H2‐, air‐, and O2‐based pigments, the coloration mechanism for the Pr‐colored zircon was systematically unveiled: both Pr4+ and Pr3+ coexist invariably in the pigments, while the former contributes primarily to the ligand‐to‐metal charge transfer from O2p to Pr(IV)4f for the blue–violet absorption to generate the yellow hue, and the latter is inclined to discolor the pigments. Therefore, an oxidizing atmosphere is preferable to produce brilliant Pr‐ZrSiO4 pigments with enhanced chromatic properties. The stark spectroscopic distinctions between the wide‐band absorption from the nonluminescent tetravalency and the narrow‐band absorption from the luminescent trivalency can expand our understanding to the rare‐earth‐based inorganic pigments.

Density functional theory investigation of Pr adsorption on the anatase TiO[formula omitted](101) surface for photovoltaic applications

We present first-principles density functional theory calculations for the structural, electronic, and optical properties for the Pr-doped anatase TiO2(101) surface. The DFT+U formalism is used to describe the strong correlations arising from the localized Ti 3d and Pr 4f orbitals. The incorporation of Pr into the surface results in the impurity states fall into the band gap, improving the optical activity of the TiO2(101) surface both in the UV–visible and the near-IR range. In addition, we probe the adsorbate–dopant interaction using benzoic acid, a prototypical dye molecule as an example. Molecular adsorption energies as well as the optical properties are improved as a result of the inclusion of Pr.

Strong Electronic Orbit Coupling between Cobalt and Single-Atom Praseodymium for Boosted Nitrous Oxide Decomposition on Co3O4 Catalyst.

Nitrous oxide (N2O) has gained increasing attention as an important noncarbon dioxide greenhouse gas, and catalytic decomposition is an effective method of reducing its emissions. Here, Co3O4 was synthesized by the sol-gel method and single-atom Pr was confined in its matrix to improve the N2O decomposition performance. It was observed that the reaction rate varied in a volcano-like pattern with the amount of doped Pr. A N2O decomposition reaction rate 5-7.5 times greater than that of pure Co3O4 is achieved on the catalyst with a Pr/Co molar ratio of 0.06:1, and further Pr doping reduced the activity due to PrOx cluster formation. Combined with X-ray photoelectron spectroscopy, X-ray absorption fine structure, density functional theory and in situ near-ambient pressure X-ray photoelectron spectroscopy, it was demonstrated that the single-atom doped Pr in Co3O4 generates the "Pr 4f-O 2p-Co 3d" network, which redistributes the electrons in Co3O4 lattice and increases the t2g electrons at the tetracoordinated Co2+ sites. This coupling between the Pr 4f orbit and Co2+ 3d orbit triggers the formation of a 4f-3d electronic ladder, which accelerates the electron transfer from Co2+ to the 3π* antibonding orbital of N2O, thus contributing to the N-O bond cleavage. Moreover, the energy barrier for each elementary reaction in the decomposition process of N2O is reduced, especially for O2 desorption. Our work provides a theoretical grounding and reference for designing atomically modified catalysts for N2O decomposition.

First-Principles Study of the RKKY Interaction and the Quadrupole Order in the Pr 1-2-20 Systems PrT2Al20 (T = Ti, V)

Electronic states and quadrupole orders in the Pr 1-2-20 systems PrT2Al20 (T=Ti, V) are investigated on the basis of the first-principles calculations. The effective 196 orbital model is derived to reproduce the first-principles electronic structures of LaT2Al20 (T=Ti, V) without contribution from the Pr 4f electrons which are considered to be well localized and is employed to calculate the Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions between quadrupole and octupole moments of the Pr ions. Within the random phase approximation for the RKKY Hamiltonian, the most divergent susceptibility is found to be the quadrupole one for the wave vector Q = (0,0,0) in the case of PrTi2Al20 while that for Q = (pi/a,0,pi/a) in the case of PrV2Al20 as consistent with experimental observations in the both cases which exhibit the ferro-quadrupole (FQ) and the antiferro-quadrupole (AFQ) orders, respectively. We also discuss the ordered states using the mean-field approximation and find that, in the case of PrTi2Al20, the 1st-order phase transition to the O20 FQ order with a tiny discontinuity takes place as predicted by the Landau theory. In the case of PrV2Al20, the system exhibits two distinct O22 AFQ orders, AFQ-I and AFQ-II, and shows subsequent two phase transitions, the 2nd-order one from normal to AFQ-I and the 1st-order one from AFQ-I to AFQ-II, that may be responsible for the double transitions observed by specific heat measurements.

Rare-earth moment reduction and local magnetic anisotropy in Pr2Fe14B and Tm2Fe14B

Magnetization curves for Pr2Fe14B single crystals were measured between 300 K and 900 K. The saturation magnetization Ms along the [100] direction was found to be 3% to 6% smaller than that for the [001] direction, not only at 300 K but also up to the Curie temperature. Published magnetization curves for Tm2Fe14B single crystals were reexamined, in which Ms along the [001] direction exceeds that for the [100] direction. We attributed these differences in Ms to the reduction of the rare-earth (R) moment when forced to be aligned along the hard direction by external fields. Significant anisotropy was observed in the paramagnetic susceptibility χ up to 900 K in the Pr2Fe14B (R = Pr) system. Based on the crystalline electric field parameters for R = Pr and Tm systems obtained by first-principles calculations, we numerically evaluated the magnetization and paramagnetic susceptibility at high temperatures. The differences in Ms and χ obtained from the calculation were in good agreement with the experiments. We found that the reduction rate for the Pr moment at the 4f site is much smaller than that at the 4 g site. This result suggests a crucial decrease in the local magnetic anisotropy at the Pr(4f) site.

Insight into mechanical and thermodynamic properties of Al2Si2La and Al2Si2Pr from first-principles calculations

The crystal structures, stability, mechanical behaviors, thermodynamic properties and electronic structures of Al2Si2La and Al2Si2Pr compounds have been investigated by means of first-principles calculations. It is revealed from formation enthalpies that Al2Si2La exhibit much more thermodynamically stability. According to the results of elastic constants, Al2Si2Pr has stronger incompressibility, stronger shape deformation resistance and higher stiffness. It can be concluded from Debye temperature and minimum thermal conductivity that Al2Si2Pr and Al2Si2La exhibit nearly the same thermal conductivity. Electronic structures results demonstrate that the Al–Si bonds in Al2Si2La and Al2Si2Pr are attributed to the hybridization of Al 3s state, Al 3p state and Si 3p state, while RE–Si bonds are the contribution of Si 3p state and La 5d or Pr 4f state in Al2Si2La and Al2Si2Pr, respectively.

Complex magnetic properties associated with competing local and itinerant magnetism in {text {Pr}}_2 {text {Co}}_{0.86} {text {Si}}_{2.88}

Ternary intermetallic compound {text {Pr}}_2 {text {Co}}_{0.86} {text {Si}}_{2.88} has been synthesized in single phase and characterized by x-ray diffraction, scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM-EDX) analysis, magnetization, heat capacity, neutron diffraction and muon spin rotation/relaxation (muSR) measurements. The polycrystalline compound was synthesized in single phase by introducing necessary vacancies in Co/Si sites. Magnetic, heat capacity, and zero-field neutron diffraction studies reveal that the system undergoes magnetic transition below sim4 K. Neutron diffraction measurement further reveals that the magnetic ordering is antiferromagnetic in nature with an weak ordered moment. The high temperature magnetic phase has been attributed to glassy in nature consisting of ferromagnetic clusters of itinerant (3d) Co moments as evident by the development of internal field in zero-field muSR below 50 K. The density-functional theory (DFT) calculations suggest that the low temperature magnetic transition is associated with antiferromagnetic coupling between Pr 4f and Co 3d spins. Pr moments show spin fluctuation along with unconventional orbital moment quenching due to crystal field. The evolution of the symmetry and the crystalline electric field environment of Pr-ions are also studied and compared theoretically between the elemental Pr and when it is coupled with other elements such as Co. The localized moment of Pr 4f and itinerant moment of Co 3d compete with each other below sim20 K resulting in an unusual temperature dependence of magnetic coercivity in the system.

Experimental and Theoretical Study of the Electronic Structures of Lanthanide Indium Perovskites LnInO3.

Ternary lanthanide indium oxides LnInO3 (Ln = La, Pr, Nd, Sm) were synthesized by high-temperature solid-state reaction and characterized by X-ray powder diffraction. Rietveld refinement of the powder patterns showed the LnInO3 materials to be orthorhombic perovskites belonging to the space group Pnma, based on almost-regular InO6 octahedra and highly distorted LnO12 polyhedra. Experimental structural data were compared with results from density functional theory (DFT) calculations employing a hybrid Hamiltonian. Valence region X-ray photoelectron and K-shell X-ray emission and absorption spectra of the LnInO3 compounds were simulated with the aid of the DFT calculations. Photoionization of lanthanide 4f orbitals gives rise to a complex final-state multiplet structure in the valence region for the 4fn compounds PrInO3, NdInO3, and SmInO3, and the overall photoemission spectral profiles were shown to be a superposition of final-state 4fn–1 terms onto the cross-section weighted partial densities of states from the other orbitals. The occupied 4f states are stabilized in moving across the series Pr–Nd–Sm. Band gaps were measured using diffuse reflectance spectroscopy. These results demonstrated that the band gap of LaInO3 is 4.32 eV, in agreement with DFT calculations. This is significantly larger than a band gap of 2.2 eV first proposed in 1967 and based on the idea that In 4d states lie above the top of the O 2p valence band. However, both DFT and X-ray spectroscopy show that In 4d is a shallow core level located well below the bottom of the valence band. Band gaps greater than 4 eV were observed for NdInO3 and SmInO3, but a lower gap of 3.6 eV for PrInO3 was shown to arise from the occupied Pr 4f states lying above the main O 2p valence band.

Eliminating the isolated states from the band structure of doped TiO2: A first principle study

Band structure of anatase [Formula: see text] could be modified by doping foreign atoms. With ab-initio calculations, considering praseodymium, nitrogen and gadolinium as potential dopants, some mono-, co- and tri-doped models are introduced. The structure modification due to each model is compared with a standard [Formula: see text] system. Pr doping reduced the band gap of [Formula: see text] by introducing Pr 4f states below the conduction band, and the Fermi level appears below the conduction band minimum. The addition of nitrogen in Pr-doped [Formula: see text] pushed back the Fermi level to its intrinsic position while reducing the band gap. The tri-doped system comprising of Pr, N and Gd as dopants provided a populated band gap. The impurity states associated with Gd appeared in the middle of the band gap. The density of states analysis reveals that Pr 4f states change the location of N 2p states in the band structure. Instead of appearing as isolated states, the N 2p states are mixed with O 2p states while the Pr 4f states are coupled with the Ti 3d states in Pr, N-[Formula: see text]. The Pr, N, Gd tri-doped [Formula: see text] system provided strong visible light absorption due to the stepwise transition of electrons by Gd f states. While providing reasonable visible light absorption, the Pr, N-[Formula: see text] is expected to provide strong visible light photoactivity due to the clear band gap. Due to the absence of isolated states, the generated photo-excited carriers would be efficiently utilized in the oxidation/reduction processes.

Synthesis and magnetic properties in quaternary Ca1−x Pr x Co2As2 single crystals

Series of Ca1−x Pr x Co2As2 (x = 0, 0.10, 0.25, 0.4, 0.6, 0.75, 0.85, 1) single crystals have been synthesized in order to clarify the variation of magnetic order from antiferromagnetic (AFM) in CaCo2As2 to ferromagnetic (FM) in PrCo2As2. It is found that the lattice constant of c-axis are contracted with the introduction of Pr into Ca sites in CaCo2As2. Electronic transport measurements reveal the metallicity in this system. Systematic magnetic measurements and analysis show that substituting only 10% of Pr for Ca changes the magnetic ground state from A-type AFM ordering of Co magnetic moment in CaCo2As2 to FM ordering in Ca1−x Pr x Co2As2 (0.1 ⩽ x ⩽ 1). Most importantly, the abrupt drop of low temperature magnetic susceptibility below T FiM with x ⩾ 0.25 and the observed magnetic pole reversal with x ⩾ 0.4 suggests an AFM coupling between Co 3d and Pr 4f magnetic sublattice. Finally, a detailed magnetic phase diagram in this system has been obtained.

Strain-induced spontaneous Hall effect in an epitaxial thin film of a Luttinger semimetal

Pyrochlore iridates have provided a plethora of novel phenomena owing to the combination of topology and correlation. Among them, much attention has been paid to [Formula: see text], as it is known as a Luttinger semimetal characterized by quadratic band touching at the Brillouin zone center, suggesting that the topology of its electronic states can be tuned by a moderate lattice strain and external magnetic field. Here, we report that our epitaxial [Formula: see text] thin films grown by solid-state epitaxy exhibit a spontaneous Hall effect that persists up to 50 K without having spontaneous magnetization within our experimental accuracy. This indicates that the system breaks the time reversal symmetry at a temperature scale that is too high for the magnetism to be due to Pr 4f moments and must be related to magnetic order of the iridium 5d electrons. Moreover, our analysis finds that the chiral anomaly induces the negative contribution to the magnetoresistance only when a magnetic field and the electric current are parallel to each other. Our results indicate that the strained part of the thin film forms a magnetic Weyl semimetal state.

Promoted methane activation on doped ceria via occupation of Pr(4f) states

Steam reforming of the methane stream obtained from biomass gasification is a potential route for sustainable syngas (CO + H2) and hydrogen production. The rate-limiting step for the reactions involved in methane steam reforming (MSR) is thought to be CH4 activation. Praseodymium-doped ceria-based catalysts, with easily reducible Pr cations and high oxygen storage capacity, could be attractive for MSR. In this work, we performed density functional theory (DFT) calculations to examine the activity of a low Pr-doped CeO2(1 1 1) surface for methane reforming. The results show a significant lowering (0.48 eV) of the energy barrier for methane activation via homolytic H3CH bond cleavage. This can be mainly explained by the easy occupation of Pr(4f) gap states by electrons transferred from adsorbed hydrogen species. The promotion of methane activation upon Pr doping of ceria was corroborated with methane temperature-programed reduction (CH4-TPR) experiments conducted in both Ce0.95Pr0.05O2 and CeO2 samples.

Resonant x-ray scattering study on electronic hybridization in unconventional ordered phase of PrRu4P12

PrRu4P12, which undergoes a metal-insulator transition at TMI ∼ 63 K, has been investigated by resonant x-ray scattering technique at the Pr L3-edge, the P K-edge, and the Ru L3-edge, in which element and orbital selective electronic states can be clarified. Resonating energy spectra at the 111 reflection were found at the Pr L3-edge and P K-edge, while it was not observed at the Rh L3-edge. This is the first observation of quite large resonant signal at the P K-edge. This result is considered as a direct evidence for the strong Pr 4f and P 3p hybridization effect on the unconventional ordered phase accompanied by the insulator state.

Giant Rashba effect at the topological surface of PrGe revealing antiferromagnetic spintronics

Rashba spin-orbit splitting in the magnetic materials opens up a new perspective in the field of spintronics. Here, we report a giant Rashba spin-orbit splitting on the PrGe [010] surface in the paramagnetic phase with Rashba coefficient αR = 5 eVÅ. We find that αR can be tuned in this system as a function of temperature at different magnetic phases. Rashba type spin polarized surface states originates due to the strong hybridization between Pr 4f states with the conduction electrons. Significant changes observed in the spin polarized surface states across the magnetic transitions are due to the competition between Dzyaloshinsky-Moriya interaction and exchange interaction present in this system. Presence of Dzyaloshinsky-Moriya interaction on the topological surface give rise to Saddle point singularity which leads to electron-like and hole-like Rashba spin split bands in the bar{{boldsymbol{Z}}}^{prime} -bar{{boldsymbol{Gamma }}}-bar{{boldsymbol{Z}}} and bar{{boldsymbol{X}}}^{prime} -bar{{boldsymbol{Gamma }}}-bar{{boldsymbol{X}}} directions, respectively. Supporting evidences of Dzyaloshinsky-Moriya interaction have been obtained as anisotropic magnetoresistance with respect to field direction and first-order type hysteresis in the X-ray diffraction measurements. A giant negative magnetoresistance of 43% in the antiferromagnetic phase and tunable Rashba parameter with temperature makes this material a suitable candidate for application in the antiferromagnetic spintronic devices.

Effects of on-site Coulomb interaction (U) on the structural and electronic properties of half-metallic ferromagnetic orthorhombic Pr0.75Na0.25MnO3 manganite: a LDA + U calculation and experimental study

In this study, the structural, electronic, and half-metallic properties of monovalent-doped Pr0.75Na0.25MnO3 manganite were investigated via density functional theory (DFT) with local density approximation (LDA) and local density approximation plus Hubbard U parameter (LDA + U). The effect of on-site Coulomb interaction on the structural and electronic properties of REMnO3 (RE = Pr, Nd, La) manganites, which consist of strongly interacting RE 4f and transition metal Mn 3d electrons, were studied. The strong Coulomb repulsion between electrons was corrected using the Hubbard parameter U, which ranged from 2 to 6 eV for Mn 3d and was set at 6 eV for Pr 4f. The calculated results showed that the structural parameters, charge and spin densities, and the total and partial densities of states of Pr0.75Na0.25MnO3 manganite were sensitive to the change in U value. The crystal structure and energy band gap of Pr0.75Na0.25MnO3 manganite were calculated using LDA + U with the optimized U value of 2 eV for Mn 3d. The results calculated with a U value of 2 eV showed better agreement with the experimental data compared with those calculated with U values of 4 eV and 6 eV. Interestingly, the LDA + U-based calculations revealed that Pr0.75Na0.25MnO3 manganite has a half-metallic ferromagnetic character. The majority-spin electrons exhibited metallic behavior, whereas the minority-spin electrons exhibited insulating gaps of 2.50, 3.28, and 4.20 eV for the U values of 2, 4, and 6 eV, respectively. The calculated band structure and density of states indicated that the on-site Coulomb repulsion U significantly influenced the hybridization of O 2p with Mn 3d orbitals at the valence and conduction bands.

Magnetic interactions in praseodymium ruthenate Pr3RuO7 with fluorite-related structure

Solid solutions Pr3(Ru1-xTax)O7 (0≤x≤1.0) and (Pr1-xYx)3RuO7 (0≤x≤0.7) were obtained as a single phase compound. They crystallize in an orthorhombic superstructure derived from that of the cubic fluorite with space group Cmcm. The results of the Rietveld analysis for X-ray diffraction profiles of Pr3(Ru1-xTax)O7 showed that Ru and Ta atoms are randomly situated at the six-coordinate 4b site. For (Pr1-xYx)3RuO7, with increasing the concentration of Y ions (x value), the smaller Y ions occupy selectively the seven-coordinate 8g site rather than the eight-coordinate 4a site.Through magnetic susceptibility measurements for Pr3(Ru1-xTax)O7, the antiferromagnetic transition temperatures decrease linearly with increasing x value, and at x=0.75 no magnetic ordering was found down to 1.8K, indicating the magnetic interaction is not one-dimensional, but three-dimensional. On the other hand, the antiferromagnetic transition temperature for (Pr1-xYx)3RuO7 decreases with increasing x value, but above x≥0.50 it becomes constant (~12K). This result indicates that Pr3+ ions at the seven-coordinate site greatly contribute to the antiferromagnetic interactions observed in (Pr1-xYx)3RuO7.Density functional calculations of Pr3RuO7 demonstrate that the electronic structure gives insulating character and that oxygen 2p orbitals hybridize strongly with Ru 4d orbitals in the valence band (VB). Near the top of VB, the Pr 4f orbitals at the seven-coordinated site also show a weak hybridization with the O(1) 2p orbitals. The Ru-O(1)-Pr superexchange pathway take part in three-dimensional magnetic interaction and play an important role in an enhancement of long-range magnetic ordering.

Hard X-ray Photon-in Photon-out Spectroscopy as a Probe of the Temperature-Induced Delocalization of Electrons in Nanoscale Semiconductors

Hard X-ray photon-in photon-out spectroscopy has so far mainly been applied to investigate fundamental physical phenomena in superconductors and chemical reactivity of bioinorganic, photocatalytic, and catalytic materials. Here, we show, with the example of Pr6O11 nanoparticles, an n-type semiconductor, how high-energy resolution fluorescence detected (HERFD) X-ray absorption near edge structure (XANES) can be used to track the changes of partially filled f-bands. We observe a reversible variation of the spectral features related to the tetravalent Pr ions upon heating and cooling, whereas structural and chemical transformations can be excluded. We assign these changes to the occupancy of the O 2p–Pr 4f band and show that they directly relate to changes in the electrical conductance. Our results demonstrate how HERFD-XANES can be used to particularly study in situ the electronic properties of f-electrons in a semiconductor and how this method can be further extended to other classes of semiconducting nano...

Redox behavior of a low-doped Pr-CeO2(111) surface. A DFT+U study

In this work, we investigated the redox behavior (donation and replenishing of oxygen) of a low praseodymium (Pr)-doped CeO2(111) surface. We considered a 3.7at.% Pr doping and performed density functional calculations using the GGA formalism with the ‘U’ correction on Ce(4f) and Pr(4f) orbitals. Our results indicate that Pr doping promotes oxygen donation by lowering the energy necessary to form surface anionic vacancies. When the Ce0.963Pr0.037O2(111) surface donates one oxygen, the two excess electrons locate on Pr and Ce cations and reduce them to Pr3+ and Ce3+ ones. Praseodymium doping also favors the activation of O2 molecule on surface O-holes, leading to formation of a superoxide (O2−) radical as well as to reoxidation of the Ce3+ cation to Ce4+ one. Additionally, we used the CO molecular adsorption for testing the reactivity of those superoxide species. The calculations expose the ability of these radicals to oxidize CO forming a CO2 molecule floating on the surface. However, when the superoxide is in the immediate vicinity of Pr dopant a carbonate-type species is formed. Our theoretical results may help to gain insight into redox properties and improved catalytic performance of low-doped Pr-CeO2 solids.