Incorporation Of Ce Research Articles

Effect of ceria content in Ni–Ce–Al catalyst on catalytic performance and carbon/coke formation in dry reforming of CH4

In this study, to enhance the catalytic activity and minimize the carbon/coke formation, cerium incorporated alumina-supported new Ni–Ce–Al catalysts were investigated in dry reforming of biogas. Ni–Ce–Al catalysts were synthesized by the modified one-pot sol-gel method in an inert environment. To determine the effect of the Ce/Al ratio on physicochemical properties of catalysts and their activity, Ni (5 wt %) catalysts with different Ce/Al ratios (0/1, 1/2, 1/1, 2/1 b y wt.) were tested in a fixed-bed flow reactor using an equimolar ratio of CH4/CO2/Ar gas mixture. To explain the correlation between catalytic activity and catalyst properties, characterization studies were carried out by using N2 adsorption-desorption isotherms, XPS, XRD, SEM-EDS, TEM, ICP-OES, DRIFT, O2-TPO and TGA methods before and after activity tests. XRD analysis showed that both CeO2 and γ-Al2O3 crystalline phases with metallic Ni having different peak intensities were separately formed in all the catalysts. Among the catalysts of different Ce/Al ratios, the Ni–1Ce–1Al catalyst containing equal amounts of Al and Ce has the smallest CeO2 crystallite size. This catalyst also has the highest pore diameter and volume. XPS analysis showed that Ce incorporation into the Ni-based Al2O3 catalyst decreased the NiAl2O4 formation. DRIFT analysis indicated that the addition of ceria into the support material decreased the Lewis acidity of alumina. During 25-h long-term activity test, the conversions of CH4 and CO2 obtained with the catalyst Ni–1Ce–1Al (Ce/Al ratio is 1/1) were approximately the same and averaged 76% and 85%, respectively. This behavior of the catalyst indicates its high stability. TGA, XRD and SEM analyzes performed with the used Ni–1Ce–1Al and Ni–Al catalysts show very little carbon formation in the catalyst containing equal weights of Ce and Al compared to the catalyst without Ce. This result shows that the addition of cerium to the catalyst structure prevents carbon deposition due to its special oxygen mobility. This study showed that the crystallite size of CeO2 in the catalyst structure strongly influences preventing carbon accumulation in the dry reforming reaction.

Heterogeneous engineering of nickel-iron sulfide with cerium-promoted reconstruction for enhanced oxygen evolution

The development of efficient oxygen evolution reaction (OER) electrocatalysts is critical for electrochemical water splitting. Herein, a cerium-doped Ni3S2/NiS/FeS heterogeneous structure nanoparticle supported on nickel foam (Ce-NiSx/FeS/NF) is prepared as a precatalyst for OER reaction in alkaline solution. The heterointerfaces of NiSx/FeS adjust the electronic structure and expose more active sites, accelerating the OER process. The Ce incorporation promotes the in situ reconstruction and oxidation of the sulfides to the heterogeneous NiOOH/FeOOH, which act as the actual active sites for the OER reaction. Thus, the Ce-NiSx/FeS/NF demonstrates excellent OER performance with a low overpotential of 125 mV at 10 mA cm−2 and long-term robustness. Additionally, a water splitting device is constructed using Ce-NiSx/FeS/NF and commercial Pt/C/NF as the anode and cathode, respectively. This device achieves a current density of 10 mA cm−2 at 1.38 V with 50 h of reliable continuous operation at 1.78 V. Density functional theory (DFT) calculation confirms that the active sites of Ce-NiOOH/FeOOH optimize intermediates adsorption energy (higher OH− adsorption energy and lower O2 desorption energy) and provide faster OER kinetics, conducive to the OER process. This work presents the concept of rare-earth-doping promotes reconstruction of heterogeneous transition-metal-based compounds for the development of high-performing OER electrocatalysts.

Modulating the Electronic Structure of α-Fe2O3 by Doping Atomically Dispersed Ce for the Transfer Hydrogenation of Nitroaromatics Using Stoichiometric Hydrazine Hydrate

The metal-oxide-catalyzed transfer hydrogenation of nitroarenes to anilines by hydrazine hydrate has been widely reported; however, the risk of explosion resulting from excess hydrazine hydrate and high temperatures and complex preparations of these catalysts immensely hinder their industrial application. Herein, we use a simple co-precipitation method to synthesize atomically dispersed Ce-doped α-Fe2O3 (Ce0.025-Fe2O3-350 °C), which can completely reduce nitroarenes using stoichiometric hydrazine hydrate at room temperature, where the parent α-Fe2O3 is inactive. A thorough characterization indicates that the incorporation of Ce into the crystal lattice of α-Fe2O3 reorganizes the electronic structure of the surrounding Fe, such that the Lewis acidity of Fe2O3 is enhanced, which is the key for the room-temperature decomposition of N2H4·H2O. The structure is also beneficial for the adsorption of nitroarene, leading to the weakening of the N–O bonds. Mechanistic experiments and DFT calculations demonstrate that the reduction proceeds through Ph-NO2 → Ph-NHOH → Ph-NH2 without the widely recognized Ph-NO intermediate. Moreover, Ce0.025-Fe2O3-350 °C exhibits good stability in a continuous-flow reaction.

Synthesis of the cerium doped Gd3Al3Ga2O12-based glass nanoceramics: Luminescence and optical absorption properties

Cerium doped gadolinium gallium aluminum garnet (Gd3Al3Ga2O12, GAGG) was synthesized in the glass ceramics form by the crystallization from Gd2O3–Al2O3–Ga2O3–SiO2–CeO2 glass in the following weight proportion: 101 : 26: 47 : 25: 1. The spatial distribution and incorporation of Ce into the GAGG ceramic grains as well as the luminescence and scintillation performance are studied carrying out correlated experiments of photo-, radio- and cathodoluminescence including decay kinetics as well as energy dispersive X-ray spectroscopy combined with scanning electron microscopy. Optical absorption features were investigated using photothermal deflection spectroscopy. Cerium stays within the material mostly in the Ce3+ charge state. Its distribution in the bulk of the sample exhibits irregular trend indicating the tendency to coalesce in the middle.

Unravelling the synergy of Ce dopant and surface oxygen vacancies confined in FeTiO3 perovskite for peroxymonosulfate activated degradation of wide range of pollutants

In this study, ferrite titanate (FeTiO3) as a low-cost, eco-friendly and a new type of perovskite catalyst was utilized in sulfate-based advanced oxidation process. Structural and chemical modulation strategy was implemented by doping cerium (Ce) atoms via hydrothermal technique. The morphological, optical and structural properties of the catalysts were investigated with the aid of XRD, SEM-EDS, TEM, XPS, UV–vis DRS and PL analyses. XPS analysis confirmed that Ce existed as Ce(III) and Ce(IV) oxidation states, indicating the presence of Ce(III)/Ce(IV) redox couple, which assisted the oxidative degradation process. The introduction of Ce into the FeTiO3 structure also resulted in higher content of oxygen vacancies, regulated the redox cycle, and reduced the energy barrier for Fenton activation. The photocatalytic performances of Ce-doped FeTiO3 perovskites for peroxymonosulfate activation were investigated towards removal of sunset yellow azo dye which is one of the most used synthetic food dyes. The effects of Ce concentrations in FeTiO3, initial solution pH, water media, scavengers and re-usability were studied systematically. Moreover, the photodegradation activities of the catalyst with respect to different dye and antibiotic components were also investigated. The catalyst was proven to be stable after eight consecutive runs. The findings showed that the incorporation of Ce as a peroxymonosulfate activator greatly facilitated the degradation of water pollutants.

Initiating highly efficient (Bi,Ce)2(O,S)3−xoxysulfide catalysts with rich oxygen vacancies for hydrogen evolutionviaadjusting valence band configuration

Converting Bi2S3into an efficient PHER catalyst by defect engineering to form solid solutions with the incorporation of Ce and O into Bi2S3for bimetal–chalcogen (Bi,Ce)2(O,S)3−xcatalysts.

Electrospinning of cotton-like fibers based on cerium-doped sol–gel bioactive glass

In this study, Ce-doped calcium silicate-based bioactive glass sols were electrospun under well-defined parameters and heat-treated to obtain cotton-like fibrous structures. The 3D structures comprised long and entangled fibers with interconnected pores, and the successful incorporation of Ce was confirmed by EDX analysis. The fibers were highly hydrophilic and demonstrated in vitro bioactivity after immersion in simulated body fluid. The fibers were non-cytotoxic toward keratinocytes and did not inhibit the wound closure process, which was characterized in vitro.

Effect of Ce incorporation into carbon layer on the performance of silicon-carbon composite as anode for LIBs

Volume expansion of silicon during lithiation limits its use as a commercial anode material. Carbon coating on silicon surfaces can buffer the phase change stress of silicon and enhance conductivity. In this work, the effect of the incorporation of rare earth element Ce in the carbon layer on the electrochemical properties of silicon-carbon composites was investigated. After mixing according to a particular procedure, cerium nitrate, micron silicon, and sodium alginate (SA) were calcined to obtain the silicon-carbon composite coated carbon layer incorporation Ce. The tests found that the incorporation of Ce into the carbon layer had the following effects on the performance of LIBs anode: (1) enhanced the toughness of the carbon layer and improved the cycle performance, (2) reduced the formation of SEI film and increased the first Coulombe efficiency (ICE), (3) boosted the lithium-ion conductivity of silicon-carbon composite and improved the rate capability. As a result, the electrochemical properties of Ce incorporated silicon-carbon composites (Si@C/CeO2) are significantly improved. The initial specific capacity of Si@C/CeO2 was 1848.6 mAh g-1, even micro silicon engendered strong phase change stress, still maintained 502.2 mAh g-1 after 180 cycles, and the ICE was higher than most of the silicon-carbon composites reported.

Oxygen-vacancy-assisted construction of Ce–TiO2 aerogel for efficiently boosting photocatalytic CO2 reduction without any sacrifice agent

The development of efficient photocatalysts with high activity and high selectivity remains the biggest challenge limiting the development of photocatalysis. Herein, a novel Ce-doped TiO2 aerogel (Ce–TiO2) is synthesized via a simple one-step sol-gel technique, which integrates simultaneously supercritical drying, heat treatment, nano structuring, and self-diffusion for the formation of the Ce embedded in porous TiO2 matrix with strong coupling. The Ce–TiO2 aerogel exhibits typically homogeneous structures, and the resulting Ce–TiO2 aerogel shows an extremely large BET specific surface area of 246.53 m2/g, which is responsible for the much-enhanced photocatalytic active sites. The incorporation of Ce has induced an impurity level in the band gap of the pristine TiO2 aerogel, extending the light response range to the visible region. Meanwhile, the structural and compositional advantages are exploited to achieve fast separation and transfer of charge carriers. The yields of CH4 and CO are 0.6 and 2.1 μmol/(g·h) under visible light without any additional co-catalysts or sacrificial agents, which are 1.4 and 15.6 times as high as those of pristine TiO2 aerogel. In addition, the yields of CH4 and CO are as high as 10.3 and 26.9 μmol/(g·h) under simulated solar spectrum conditions, which are 34.3 and 1.6 times as high as those of pristine TiO2 aerogel. The density function theory (DFT) calculation confirms that the resulting Ce–TiO2 aerogel enables efficient H2O and CO2 adsorption and activation through the Ce cooperation and O vacancy, which greatly improves photocatalytic CO2 reduction. This work reveals the development of aerogel photocatalyst for the photoreduction of CO2 with H2O and CO2 as feedstock.

Resource utilization of high concentration SO2 for sulfur production over La–Ce-Ox@ZrO2 composite oxide catalyst

Sulfur dioxide is one of the main causes of air pollution such as acid rain and photochemical smog, and its pollution control and resource utilization become an important research direction of air pollution control. The active component La–Ce-Ox is loaded on SiO2, γ-Al2O3, TiO2 and ZrO2, and the La–Ce-Ox@ZrO2 exhibits the best catalytic activity. By adjusting the loading amount of La–Ce-Ox, La–Ce-Ox@ZrO2 with different mass fractions was prepared. The results show that the activity of 15%La–Ce-Ox@ZrO2 catalyst is the best. The SO2 conversion is 100%, and the S yield and S selectivity are more than 96% at 350 °C. According to the analysis results of H2-TPR, CO2-TPD and NH3-TPD, ZrO2 as a support not only reduces the acidity of the catalyst, but also improves the weak alkaline sites of the catalyst, which is conducive to the adsorption and activation of SO2 molecules at low temperature. The incorporation of La and Ce increases the oxygen concentration adsorbed on the catalyst. The strong interaction between the support ZrO2 and the active component La–Ce-Ox is conducive to the electron transfer between the active component and the support, and improves the activity of the catalyst. For the 15%La–Ce-Ox@ZrO2, the main reaction intermediates are weakly adsorbed SO2 (SO32−), bicoordinated CO32−, monodentate carbonate and CO in the gas phase. Therefore, the catalytic reaction follows both L-H and E-R mechanisms.

Structural, electrical, and magnetic properties of Ce and Fe doped SrTiO3

Here, we report on the structural, vibrational phonon, electrical, and magnetic properties of undoped strontium titanate SrTiO3, Ce doped Sr1−xCexTiO3, and (Ce, Fe) co-doped Sr1−xCexTi1−yFeyO3 samples synthesized through solid state reaction route. The Rietveld refined powder x-ray diffraction analysis confirmed the cubic Pm-3m phase in our as-synthesized samples. We observed grain size reduction in SrTiO3 from scanning electron micrographs due to the incorporation of Ce and Fe dopants. The sample purity in terms of chemical species identification has been confirmed from energy-dispersive x-ray spectroscopy. The characteristic phonon modes in our samples are identified using room temperature Raman spectroscopy and benchmarked against existing relevant experimental observations. The incorporation of Ce and Fe as substitutional dopants in SrTiO3 unit cell was confirmed from the absence of absorption at 480, 555, 580, and 1635 cm−1 band in Fourier transform infrared spectra. The 3% Ce doping in Sr0.97Ce0.03TiO3 sample may have induced ferroelectric order, whereas the undoped SrTiO3 (STO) revealed lossy paraelectric nature. In the case of (Ce = 3%, Fe = 10%) co-doped Sr0.97Ce0.03Ti0.90Fe0.10O3 sample, we observed ferromagnetic hysteresis with orders of magnitude enhancement in remnant magnetization and coercivity as compared to undoped STO sample. This long range robust ferromagnetic order may have originated from F-center mediated magnetic interaction.

How does the metal doping in mixed metal MOFs influence their photodynamics? A direct evidence for improved photocatalysts

Mixed-metal organic frameworks (MMOFs) have arisen as one of the most promising photocatalysts for a wide number of reactions. In general, the introduction of a second or even a third metal atom in the MOFs metal cluster, having a better overlap with the π∗ orbital of the organic linker, enhances the photocatalytic activity of the MOFs. This can be a consequence of a more favorable ligand-to-cluster charge transfer (LCCT) process in the MMOFs, which in fact generates a higher population of long-lived charge-separated states (CSSs), the latter being the driving force of a photocatalytic reaction. However, proving a direct relation between these photo processes and the improved photocatalytic performance in MMOFs frequently remains elusive. Hence, herein we perform an exhaustive and systematic spectroscopic and photodynamical characterization of three UiO-66-NH2-type MOFs, where the metal cluster composition is varied from 100% Zr, a mixture of Zr/Ce (80/20%), and a mixture of Zr/Ce/Ti (70/7/23%). In comparison with the linker photodynamics, we observe the opening of new deactivation channels in the MOFs, associated with the LCCT phenomenon with time constants of 5–7 ps and 70–90 ps. Upon the successive incorporation of Ce and Ce/Ti in the MOFs, the LCCT becomes more efficient, which is reflected in the quenching of the photoluminescence quantum yield and in the generation of a higher population of CSSs, demonstrated by the flash photolysis experiments. These observations are in agreement with the photodegradation of a pollutant dye, Nile Blue, where the trimetallic MOF shows higher activity than the monometallic one. Hence, our results provide conclusive experimental evidence for the relationship between the photodynamics of the MMOFs and their photocatalytic activities.

Cerium-incorporated Ni2P nanosheets for enhancing hydrogen production from overall water splitting and urea electrolysis

Hydrogen production from water splitting is a green and efficient technology for storing clean energy. Herein, cerium-incorporated Ni 2 P nanosheets are designed as trifunctional electrocatalysts to generate hydrogen by hydrothermal self-oxidation of surface nickel foam (NF) in pure water to in-situ form Ni(OH) 2 nanosheets, followed by incorporation of Ce and phosphorization. The prepared material exhibits excellent electrocatalytic performance in hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and urea oxidation reaction (UOR). When the current density is 100 mA cm −2 , the UOR potential of Ce-Ni 2 P is 1.473 V lower than that in the OER (1.731 V), suggesting a great potential to replace the sluggish OER for overall water splitting. Moreover, the Ce-Ni 2 P/NF can be applied to the electrochemical treatment of real urine electrolysis with similar performance to the urea electrolysis. Such remarkable performance is attributed to the incroporation of Ce with "Ce 3+ /Ce 4+ redox pairs", which can not only provide abundant reactive sites by the charge transfer appearance of defect sites, but also offer an effective buffering space for the pre-oxidation process from Ni 2+ to Ni 3+ . It is thus beneficial for overall water splitting and coupled urea electrolysis, providing a promising candidate for urine wastewater treatment and clean energy production. • Nanosheets are prepared by hydrothermal self-oxidation of NF in pure water. • Ce leads to the lattice distortion of Ce-Ni2P and generates abundant defects. • Such interactions between Ce and Ni2P promote HER and OER/UOR performance. • Ce-Ni2P/NF can be applied for urine wastewater treatment.

Cerium-based conversion films developed on LiAl-layered double hydroxide coatings for corrosion protection of AA7075 aluminum alloys

The paper presents several experimental results regarding the influence of various procedures applied to incorporate Ce species in hydrotalcite–type chemical conver­sion coatings on the overall corrosion performance for AA 7075 aluminum alloy as a metallic substrate. Two routes were envisaged: (i) chemical incorporation of Ce by immersion in cerium nitrate solutions and (ii) electrochemical deposition of hydro­phobic Ce - based layer involving ethanolic solutions of stearic acid and cerium nitrate. The chemical route involving immersion in cerium nitrate solutions led to the incorpo­ration of 2.46 – 6.84 wt.% Ce in the composition of the porous conversion layer. The electrochemical process facilitated the formation of a hydrophobic cerium stearate layer on porous hydrotalcite conversion coating showing water contact angles of about 132o and a higher Ce content incorporated of 6.55 – 9.73 wt.%. The corrosion performance of the Ce-based conversion coatings is also discussed.

The influence of Ce3+ codoping on upconversion in nanocrystalline NaYF4:Yb3+,Tm3+

Usually, to obtain multicolor upconversion in lanthanides, materials with different codopants, different size, chemical composition or compositional architecture are required. However, designing a material whose emission color can be tuned in-situ by an external stimulus, such as temperature, excitation pulse duration or photoexcitation density, is of great interest for many applications, but still remains a challenge. The possible solution for this issue can be achieved by intentional codoping the luminescent materials with optically active ions which can disturb or compete with other energy transfer processes, and in consequence lead to changes in relative emission intensity, thus the dominant emission color. Here we synthesized and investigated colloidal luminescent Yb3+ and Tm3+ doped NaYF4 nanoparticles which were codoped with optically active Ce3+ ions, whose relative emission intensity ratios between 1D2→3F4 (at 450 nm), 1G4→3H6 (at 475 nm), 1G4→3F4 (at 650 nm), and 3H4→3H6 (at 800 nm) were significantly dependent from external stimulus – namely temperature and/or excitation pulse length. Our results shows two fold increase in 450/800, 470/800 and 650/800 luminescence intensity bands ratios (LIR) only after incorporation of Ce3+ ions to the material, and even three-fold increase in those LIR after changing the excitation conditions (i.e. pulse width). Moreover, temperature dependent luminescence properties revealed relative sensitivity of 4%/K for the 450/800 and 470/800 bands ratio and almost 5.5%/K for the 650/800 band ratio close to 0 °C. By switching to physiological range of temperatures, the thermal sensitivity decreased to around 2%/K for the 450/800 and 470/800 bands ratio and to over 2.5%/K for 650/800 bands ratio, which should be considered as significant values and suitable for temperature sensing in practical applications. It is worth noting that the thermal sensitivity values can be further enhanced by applying different excitation pulse width. The proposed materials allows to tune its emissions as well as thermal properties by changing the dopant concentration or more importantly also in situ, through excitation scheme modifications.

Atomic cerium modulated palladium nanoclusters exsolved ferrite catalysts for lean methane conversion.

The active and stable palladium (Pd) based catalysts for CH4 conversion are of great environmental and industrial significance. Herein, we employed N2 as an optimal activation agent to develop a Pd nanocluster exsolved Ce-incorporated perovskite ferrite catalyst toward lean methane oxidation. Replacing the traditional initiator of H2, the N2 was found as an effective driving force to selectively touch off the surface exsolution of Pd nanocluster from perovskite framework without deteriorating the overall material robustness. The catalyst showed an outstanding T50 (temperature of 50% conversion) plummeting down to 350°C, outperforming the pristine and H2-activated counterparts. Further, the combined theoretical and experimental results also deciphered the crucial role that the atomically dispersed Ce ions played in both construction of active sites and CH4 conversion. The isolated Ce located at the A-site of perovskite framework facilitated the thermodynamic and kinetics of the Pd exsolution process, lowering its formation temperature and promoting its quantity. Moreover, the incorporation of Ce lowered the energy barrier for cleavage of C─H bond, and was dedicated to the preservation of highly reactive PdOx moieties during stability measurement. This work successfully ventures uncharted territory of in situ exsolution to provide a new design thinking for a highly performed catalytic interface.

Effect of Ce substitution on the local magnetic ordering and phonon instabilities in antiferromagnetic DyCrO3 perovskites

A detailed crystal structure analysis, temperature and field dependence of magnetic characteristics and phonon instabilities for different compositions (0.1 ⩽ x ⩽ 0.5) of Dy1−x Ce x CrO3 solid-solutions have been reported. All the investigated compounds exhibit distorted orthorhombic crystal structure with a distortion factor of d Oct/d Cell ∼ 6 × 10−3/3.5 ppm (for x ∼ 0.2) for Pbnm space group that follows Vegard’s law. The bonds between apical oxygen atoms (OA1) and Cr atoms stand more rigidly in comparison with the basal oxygen atoms (OB1/OB2) resulting the octahedral distortion and thereby causing the changes in phonon modes. The CrO6 octahedral tilt angle θ rotates with respect to the Miller pseudocubic axis [101] which varies from 10.36° (x = 0.1) to 12.25° (x = 0.5) and significantly influences the Ag(5) phonon stability by 3% for a change in A-site mean radius from 1.095 Å to 1.141 Å for x = 0.1 and 0.5, respectively. From the magnetization measurements we find that these series of compositions exhibit canted antiferromagnetic (AFM) ordering with Néel temperature, that increases from 151.8 K (x = 0.1) to 162 K (x = 0.5) which also manifests as a significant reduction in the magneto-crystalline anisotropy (H K ∼ 2.58 kOe → 2.07 kOe, K 1 ∼ 36.47 J m−3 → 18.97 J m−3) while maintaining the stable Γ4(G x , A y , F z ) AFM configuration. Both Dzyaloshinskii–Moriya interaction method and modified Curie–Weiss law are employed to analyse the inverse paramagnetic susceptibility, χ −1(T > ). Further, we have evaluated the symmetric (J S) and antisymmetric exchange (D AS) constants, which show progressively increasing trend (J S → 10.08 K to 11.18 K and D AS → 1.24 K to 1.73 K) with the incorporation of Ce inside the perovskite lattice. Furthermore, the role of Ce substitution on the low-temperature spin reorientation transition (T SR ∼ 3.5 K → 16.8 K pertaining to the Γ25 phase configuration) and emergence of weak-FM phase between 31 K and 45.5 K are discussed in consonance with the phonon spectra.

Dramatically promoted toluene destruction over Mn@Na-Al2O3@Al monolithic catalysts by Ce incorporation: Oxygen vacancy construction and reaction mechanism

Here, a series of Mn-Ce binary oxides loaded monolith catalysts, with the support consisting of Na-Al2O3 grown on Al mesh obtained by steam vapor treating, were prepared to attain efficient toluene destruction. On increasing CeO2 loading, the toluene conversion over prepared catalysts shows an exponential rise, with Mn-4Ce@Na-Al2O3@Al monolithic catalyst exhibiting the optimal performance, over which 90% of toluene can be decomposed at 239 °C with oxidation rate over 5.57 × 10−7 mol·g−1·s−1, obviously higher than those over 4Ce/Na-Al2O3@Al (239 °C; 0.99 × 10−7 mol·g−1·s−1) and Mn/Na-Al2O3@Al (291 °C; 4.12 × 10−7 mol·g−1·s−1). H2-TPR and XPS results reveal that the superior redox ability and the formation of MnCeOx solid solution are favorable for toluene abatement. Oxygen vacancies form easily on the surface of Ce modified samples, resulting in superior oxygen and toluene adsorption ability, as demonstrated by DFT theoretical calculation. Besides, the pathways of toluene oxidation over Mn-4Ce@Na-Al2O3@Al catalyst were identified by using the in situ DRIFTS, and the key intermediates of toluene oxidation reaction are determined to be benzoyl, benzaldehyde, and benzoate.

Incorporation of the Ce3+ activator ions in LaAlO3 crystals: EPR and NMR study

This work reports the results of EPR and NMR study of the Ce3+ incorporation in LaAlO3 single crystals grown by the micro-pulling-down method in the range of the Ce concentrations in the solid solution La1-xCexAlO3 from x ​= ​0.001 up to x ​= ​1.0. From EPR measurements, Ce3+g tensor parameters were determined as a function of Ce concentration. The g tensor has an orthorhombic symmetry even in the trigonal phase (x ​< ​0.1) suggesting that the incorporation of Ce at La site lowers the lattice symmetry near this ion. The local properties of the La1-xCexAlO3 crystals were further studied by 27Al and 139La high-resolution NMR measurements. It was found that 139La chemical shift has the Fermi contact interaction origin. It linearly increases with the Ce concentration from 0 ​ppm up to 165 ​ppm at x ​= ​0.5. Due to this strong Fermi contact interaction, separated peaks corresponding to different Ce–O–La spin transfer passways are resolved in the 139La NMR spectra. On the other hand, no Fermi contact interaction is visible in 27Al NMR spectra. However, these spectra contain a satellite peak whose intensity linearly increases with an increase of the Ce concentration leaving position of this peak unchanged. This was interpreted as manifestation of the crystal structure modification in the vicinity of Ce ions in agreement with EPR data. Thus, optical properties of Ce3+ in LaAlO3 will be determined namely by the local crystal structure near this ion.

The amino-functionalized Ce doped UiO-66 presents high potential in nuclear energy wastewater treatment

Nuclear energy is a clean and reliable alternative to traditional fuels such as gasoline and coal. However, the treatment of wastewater from nuclear plants is an issue that needs wildly exploration. In this study, novel cerium (Ce) modified aminated MOF UiO-66 was synthesized through solvothermal reactions. Using ZrCl 4 as a sacrificial template, the target product Ce-UiO-66-NH2 had been prepared by hydrothermal process. The microscopic surface morphology and characterized structure were investigated by BET, SEM, and FTIR characteristic protocols. The results revealed that Ce and amino groups have been successfully introduced on the surface of UiO-66. The absorbent Ce-UiO-66-NH2 showed its maximum specific surface area, with 823 m2/g. And the average pore size was 0.52 and 0.47 cm 3/g for Ce-UiO-66 and Ce-UiO-66-NH2, respectively. For the SEM results, both absorbents showed spherical structure, with the particles presenting 0.2–0.5μm size core–shell structures. Considering the FTIR spectra, the characteristic peaks were located at 1656, 1569, 1385, 963, 894 cm −1 wavenumbers, indicating the incorporation of Ce and -NH2. The absorbance effect was highly enhanced by suitable functionalization of the material by introducing addition metal element Ce and amino group and thus more binding storage can be used in nuclear wastewater treatment.