Oxide CeO2 Research Articles

Cerium Dioxide-Induced Abundant Cu+/Cu0 Sites for Electrocatalytic Reduction of Carbon Dioxide to C2+ Products.

In recent years, the electrochemical reduction of carbon dioxide (CO2RR) has made many advances in C2+ production. Cu+/Cu0 site is beneficial for C-C coupling process, but the oxidation state of copper cannot be well maintained during the reaction process, resulting in a decrease in catalyst activity. Based on this consideration, in this work, transition metal oxide CeO2 with a hollow cube structure and oxygen vacancies was introduced to stabilize and increase Cu+/Cu0 active sites (Ce1Cu2). The catalyst exhibits excellent CO2RR performance, with FEC2+ achieving 73.52% and jC2+ > 280 mA/cm2 at 1.26 V (vs. RHE). Ethanol is the main C2+ product and FEethanol reaches 39% at 1.26 V. The experimental results indicate that the presence of CeO2 provides a large number of oxygen vacancies and forming Cu+-O2--Ce4+ structure by the strong interaction of CeO2 and Cu NPs. The structure of Cu+-O2--Ce4+ and abundant oxygen vacancies lay a good foundation for the CO2 adsorption. Moreover, it increases the content of Cu+/Cu0 sites, effectively inhibiting hydrogen evolution reaction, promoting the C-C coupling interaction, thereby facilitating the generation of C2+ products. The DFT theoretical calculation further demonstrates that Ce1Cu2 is more inclined towards the ethanol pathway, confirming its high selectivity for ethanol.

Elucidating the intrinsic relationship between redox properties of CeO2 and CH4 oxidation activity: A theoretical perspective.

Methane (CH4) oxidation is an important reaction to reduce the greenhouse effect caused by incomplete combustion of CH4. Here, we explored the mechanism of CH4 oxidation catalyzed by CeO2 and Ni-doped CeO2, focusing on the redox properties of these catalyst surfaces, using density functional theory (DFT). We found that the barriers for CH4* activation and H2O* formation are correlated with the surface redox capacity, which is enhanced by Ni doping. Furthermore, the complete reaction mechanism is explored by DFT calculations and microkinetic simulations on bare and Ni-doped CeO2 surfaces. Our calculations suggest that the doping of Ni leads to a much higher overall reactivity, due to a balance between the CH4* activation and H2O* formation steps. These results provide insights into the CH4 oxidation mechanism and the intrinsic relationship between redox properties and the activity of CeO2 surfaces.

Experimental and theoretical study on high hydrogen storage performance of Mg(NH2)2-2LiH composite system driven by nano CeO2 oxygen vacancies

The magnesium based metal hydrogen storage composite system Mg(NH2)2-2LiH has a theoretical hydrogen storage capacity of 5.6 wt.% and is a promising hydrogen storage material for vehicles. However, its application is limited due to serious thermodynamic and kinetic barriers. Introducing efficient catalysts is an effective method to improve the hydrogen storage performance of Mg(NH2)2-2LiH. This article investigates for the first time the use of nano rare earth oxide CeO2 (∼44.5 nm) as an efficient modifier, achieving comprehensive regulation of the hydrogen storage performance of Mg(NH2)2-2LiH composite system through oxygen vacancy driven catalysis. The modification mechanism of nano CeO2 is also systematically studied using density functional theory (DFT) calculations and experimental results. Research has shown that the comprehensive hydrogen storage performance of the Mg(NH2)2-2LiH-5 wt.% CeO2 composite system is optimal, with high hydrogen absorption and desorption kinetics and reversible performance. The initial hydrogen absorption and desorption temperatures of the composite system were significantly reduced from 110/130°C to 65/80°C, and the release of by-product ammonia was significantly inhibited. Under the conditions of 170°C/50 min and 180°C/100 min, 4.37 wt.% of hydrogen can be rapidly absorbed and released. After 10 cycles of hydrogen release, the hydrogen cycle retention rate increased from 85% to nearly 100%. Further mechanistic studies have shown that the nano CeO2−x generated in situ during hydrogen evolution can effectively weaken the Mg–N and N–H bonds of Mg(NH2)2, exhibiting good catalytic effects. Meanwhile, oxygen vacancies provide a fast pathway for the diffusion of hydrogen atoms in the composite system. In addition, nano CeO2−x can effectively inhibit the polycrystalline transformation of the hydrogen evolving product Li2MgN2H2 in the system at high temperatures, reducing the difficulty of re-hydrogenation of the system. This study provides an innovative perspective for the efficient modification of magnesium based metal hydrogen storage composite materials using rare earth based catalysts, and also provides a reference for regulating the comprehensive hydrogen storage performance of hydrogen storage materials using rare earth catalysts with oxygen vacancies.

Heterogeneous Catalytic Ozonation of Pharmaceuticals: Optimization of the Process by Response Surface Methodology.

Batch heterogeneous catalytic ozonation experiments were performed using commercial and synthesized nanoparticles as catalysts in aqueous ozone. The transferred ozone dose (TOD) ranged from 0 to 150 μM, and nanoparticles were added in concentrations between 0 and 1.5 g L-1, with all experiments conducted at 20 °C and a total volume of 240 mL. A Ce-doped TiO2 catalyst (1% molar ratio of Ce/Ti) was synthesized via the sol-gel method. Response surface methodology (RSM) was applied to identify the most significant factors affecting the removal of selected pharmaceuticals, with TOD emerging as the most critical variable. Higher TOD resulted in greater removal efficiencies. Furthermore, it was found that the commercially available metal oxides α-Al2O3, Mn2O3, TiO2, and CeO2, as well as the synthesized CeTiOx, did not increase the catalytic activity of ozone during the degradation of ibuprofen (IBF) and para-chlorobenzoic acid (pCBA). Carbamazepine (CBZ) and diclofenac (DCF) are compounds susceptible to ozone oxidation, thus their complete degradation at 150 μM transferred ozone dose was attained. The limited catalytic effect was attributed to the rapid consumption of ozone within the first minute of reaction, as well as the saturation of catalyst active sites by water molecules, which inhibited effective ozone adsorption and subsequent hydroxyl radical generation (●OH).

Synergistic effect as a function of preparation method in CeO2-ZrO2-SnO2 catalysts for CO oxidation and soot combustion

The development of catalysts based on environmentally desirable components is a topical challenge. In the present work, we consider the effects of the preparation method on phase composition, porous structure, nature and distribution of active sites as well as synergistic behavior of components in two series of CeO2-ZrO2-SnO2 catalysts for soot combustion and CO oxidation. The catalysts prepared by the citrate method feature rather large SnO2 aggregates distributed on CeO2 and/or ZrO2 oxides. On the contrary, the catalysts prepared by the CTAB-templated approach feature a uniform distribution of oxide species and usually show higher activity in both CO oxidation and soot combustion. In both series, the activity and characteristics of catalysts are enhanced due to the synergistic effects arising when two or more oxide components coexist in their composition, and the degree of synergy is a function of the preparation method. The features of the most active catalysts combine (1) high specific surface area and pore volume, (2) high microstrain values, (3) coexisting oxygen vacancies of different nature, (4) high H2 consumption at low temperatures, and (5) high fraction of adsorbed active oxygen species.

Effect of CeO2 on the preparation of functional ceramsite and the adsorption effect of ammonia-nitrogen wastewater treatment

This study investigates the effect of rare earth oxide CeO2 on the physical properties of ceramsite and its efficiency in treating ammonia-nitrogen wastewater. Ceramsite was prepared from solid waste with 10 % coal gangue added as a pore-forming agent. Ceramsite sample I with CeO2 and sample II without CeO2 were prepared using pure reagents. The process parameters for both samples were optimized using an orthogonal test. Additionally, the effects of CeO2 on ceramsite performance and the treatment of ammonia-nitrogen wastewater were studied, and the adsorption mechanism of CeO2 on ammonia-nitrogen wastewater was clarified. The process parameters for preparing ceramsite sample Ⅰ were: preheating for 30 min at 600 °C, followed by roasting for 20 min at 1090 °C. The parameters for preparing ceramsite sample Ⅱ were: preheating for 30 min at 600 °C, followed by roasting time for 15 min at 1090 °C. The presence of CeO2 increased the porosity of the ceramsite by 0.89 % and the specific surface area by 0.66 m2/g. Under neutral environmental conditions of water samples, CeO2 increased the removal rate of ammonia nitrogen by 1.85 %. Ceramsite has a high porosity and specific surface area, indicating that it has abundant internal pores, a large contact area with ammonia-nitrogen, a strong ability to remove ammonia nitrogen, and resistance to erosion and water flow shear, which are conducive to the treatment of ammonia-nitrogen wastewater.

Impact of metal oxides on the selectivity of NiBi/C catalysts for high-value C-3 products in glycerol electrooxidation reaction

Enhancing the catalytic efficiency and specificity of non-noble Nickel-based catalysts for glycerol electro-oxidation reaction (GEOR) is an ongoing challenge. Recently, metal oxides have attracted attention due to their unique physical properties, such as chemical stability at high anodic potentials, presence of oxygen vacancies, which can significantly influence reaction kinetics and pathways.In this study, we explored the impact of metal oxides CeO2, SnO2, and Sb2O3 • SnO2 (ATO) on the electrochemical performance and product selectivity of NiBi/C and Ni/C catalysts in glycerol electrooxidation (GEOR). The Ni/C-X and NiBi/C-X (X= CeO2, SnO2, and ATO) catalysts were synthesized through a sodium borohydride reduction method at room temperature and comprehensively characterized using various physiochemical and electrochemical techniques.Among the composite support catalysts, Ni and NiBi/C-X, Ni/C-ATO exhibited the highest peak current density, reaching 96 mA cm-2 at 1.50 V vs. RHE. To further assess the catalysts' performance, continuous electrolysis, coupled with HPLC analysis, was conducted to determine product selectivity. Notably, NiBi/C-ATO demonstrated remarkable selectivity, achieving 100 % lactate selectivity under mild conditions. These findings contribute valuable insights into optimizing non-noble Nickel-based catalysts for GEOR, particularly highlighting the promising performance of Ni/C-ATO in terms of selectivity towards valuable products. The DFT calculations provided insight into the synergistic interactions for GEOR over Ni-Ni and Bi-Bi nanoparticles.

Influence of variable valence metal oxides on physico-chemical and antibacterial properties of semi-coated glazes

The paper presents the results of studies on the production of semi-coated glazes with antibacterial activity by introducing variable valence oxides CeO2, WO3, Bi2O3, Fe2O3, MnO2 and MoO3 into their composition. The raw polycomponent compositions were comprised of aluminosilicate multi-calcium glass frit, dolomite powder, feldspar, alumina, quartz sand, wet-enriched kaolin and refractory clay. The coatings were obtained by single firing on a ceramic-based porcelain stoneware at a temperature of 1 200 ± 5 °C in a high-speed mode for 60 ± 2 minutes. The study focused on the processes of glaze formation of coatings and the influence of the components of glaze charges on decorative and aesthetic characteristics of coatings (color, texture, gloss and whiteness). Parameters of physical and chemical properties were determined in accordance with the existing specification for the products, i. e. temperature coefficient of linear expansion, heat resistance, chemical resistance, microhardness, frost resistance, wear resistance, etc. Antibacterial activity of the coatings towards Escherichia coli ATCC 8739 and Staphylococcus aureus ATCC 6538 test strains was studied.

Electrolysis combined with magnetic CeO2/ZSM-5@Fe3O4 catalyst to boost transesterification for biodiesel production

The current transesterification for biodiesel is normally conducted with heat input and the resource is required to remove the contained water, which is complicated and costly. The novel magnetic catalyst of the bimetallic oxides of CeO2 and Fe3O4 supported on the hierarchical pore ZSM-5 was prepared and used for the biodiesel production through transesterification of palm oil with methanol under the electrolytic assistance. The prepared catalysts were characterized by SEM-EDS, TEM, FTIR, XRD, CO2/NH3-TPD, N2 adsorption–desorption and VSM, etc. The loaded cerium stimulated the particles growth and abundant catalytic active sites were obtained due to the coral-like structure and they were beneficial for transesterification. The presence of both acidic and basic sites guaranteed the strong catalytic capability of the CeO2/ZSM-5@Fe3O4 catalyst. Under the optimized transesterification condition of the catalyst dosage of 3 wt%, methanol to oil molar ratio of 18:1, reaction time of 2.5 h, electrolysis voltage of 40 V, presence of 2 % wt/wt of water added and reaction temperature of 25 ℃, the FAME yield of approximately 95 % was achieved. Also, the catalyst showed an acceptable reusability, where the FAME yield of 79 % was obtained after fourth reused cycle. In conclusion, the water in the resource promotes the electrolytic transesterification to occur efficiently at the room temperature.

Cu and Fe modified Cerium and Zirconium Oxides for the Oxidation of Cyclohexane to KA Oil

AbstractCe and Zr oxides have been tested in the oxidation of cyclohexane to KA oil because of the possibility to tune their crystal structure and redox properties by introducing defects, and of modifying their mechanical and thermal stability. The redox properties of the two oxides, prepared by the inverse microemulsion technique, have been tuned by homogeneously including Cu or Fe (10 % molar) into their structures. These modifications led to very different behaviours in terms of both KA oil productivity and K/A ratios, especially upon undergoing reduction treatment, being the reduced Cu‐modified CeO2 oxide the most active catalyst, able to produce 2.2 mmol of KA oil after 5 hours with 93.2 % selectivity (K/A 2.6). The materials obtained have been characterized by solid state analytical techniques to study their structure, morphologies as well as their bulk and surface chemistry (STEM/EDX, BET, XRD, XPS).

(Dielectric Science and Technology Poster Award, 2nd Place) Activation of Amine Chemistries for the Enhanced Particle Removal Efficiency of CeO2 Nanoparticles Via Megasonic Processing Conditions

With the persistent advancement of semiconductor technology, the demand for high-efficiency device manufacturing processes has surged. Chemical Mechanical Planarization (CMP) is a cornerstone for achieving angstrom-scale surface uniformity crucial for integrated circuits (IC) and logic devices. Shallow Trench Isolation (STI) CMP involves the selective removal of bulk oxide to electrically isolate active components on wafer surfaces. The modulation of the Ce3+ to Ce4+ surface state is essential for improved performance in both CMP and post-CMP (p-CMP) applications. Ce3+ is ideal for oxide material polishing due to its strong adherence to oxide surfaces, while Ce4+ is optimal for p-CMP cleaning, given its weak bond to oxide surfaces. Current p-CMP industry-standard methods utilize mechanical approaches, such as polyvinyl alcohol (PVA) brush scrubbing. However, this process induces high levels of shear force (SF), leading to secondary defects on the wafer surface (i.e. scratches, corrosion, increased surface roughness). To address these limitations, non-contact cleaning methods utilizing megasonic energy have emerged, which rely on generating reactive oxygen species (ROS) to induce particle removal. Thus, this study focuses on enhancing ceria particle removal during post-CMP cleaning by employing amine-based chemistries coupled with megasonic energy. While preliminary results imply that the mechanical cavitations induced by megasonic waves improve cleaning efficiency, this method will be optimized via the introduction of amine-based chemistries. Specifically, this work aims to leverage the unique properties of amines coupled with megasonic energy to facilitate enhanced ceria removal through electron donation, inducing a reduction in the oxidation state of ceria from Ce³⁺ to Ce⁴⁺. This approach improves particle removal while limiting secondary defects, enhancing redox activity induced by megasonic waves and chemical interactions. The mechanisms behind this method will be validated with CeO2 oxidation state kinetics, interfacial frictional changes, wafer surface roughness analysis, and SEM validation of particle removal efficiency.

Utilization of High Entropy Alloy (Co–Cu–Fe–Mn–Ni) and Support (CeO2) Interaction for CO2 Conversion into Syngas

AbstractHere metal support interaction (MSI) is demonstrated in a high entropy alloy (HEA: CoCuFeMnNi) supported CeO2. The HEA behaves as an active dry reforming catalyst only when it is supported over CeO2 oxide, clearly demonstrating MSI. Based on spectroscopic and microscopic observations, it is envisaged that the substitutional effect is the one that causes the lattice oxygen activation, an important active species during DRM reaction. Transient studies are performed to understand the surface chemistry of the interaction between methane and CO2 in the presence of a catalyst, which results in a methane decomposition first to generate hydrogen and carbon and followed by a CO2 reaction to give CO using deposited carbon. The experimental observations are further proven by mechanistic study with DFT calculations which show a major contribution of H‐assisted CO2 dissociation and pre‐H2 releasing carbon depositing CH4 dissociation and a minor contribution of pre‐CO releasing H2 formation. This MSI moves the d‐band center of the Co atoms of CoCuFeMnNi/CeO2 to the closest position of the Fermi level as compared to the isolated nanoparticles. This study can be taken as a proof of concept to demonstrate that MSI can be generated in the HEA/CeO2 catalysts for a generic heterogeneous gas phase reaction.

Influence of Post-Annealing Treatment on Some Physical Properties of Cerium Oxide Thin Films Prepared by the Sol–Gel Method

In this study, thin films of Cerium Oxide CeO2 were fabricated using the sol–gel technique and deposited onto a glass substrate. The annealing process was carried out at various temperatures ranging from 200 to 600 °C to investigate the structural, morphological, and optical properties of the films and their interrelations. X-ray diffraction (XRD) patterns revealed the crystalline nature of the prepared films, with film quality exhibiting enhancement with increasing annealing temperature. The average crystallite size, dislocation density, microstrain, and lattice constant were determined from XRD patterns. Higher annealing temperatures were found to increase the crystallite size values from 4.71 to 15.33 nm and decrease the dislocation density and microstrain of the unit cell. Scanning electron microscope (SEM) images illustrated the uniformity of the films, presenting a spheroid shape. Optical properties such as transmittance, absorbance, reflectance, the direct band gap, extinction coefficients, the refractive index, and optical conductivity were assessed using optical measurements. The direct optical band gap of the CeO2 film was observed to decrease from 3.99 to 3.75 eV with increasing film thickness. Using the Wemple and DiDomenico (WDD) single-oscillator model, dispersion energy parameters were calculated based on the refractive index. The nonlinear optical properties of the CeO2 thin films were evaluated using these dispersion energy parameters. The improvement of optical parameters holds significance in standardizing CeO2 thin films for various optoelectronic applications.

Impact of fission product (Ce, Sn, Sr, Se) oxides on UO2 oxidation to U3O8

In order to investigate the impact of fission products on the oxidation of spent fuel in the cladding separation process, the oxidation behavior and kinetic mechanism of UO2 and impact of M (M = Ce, Sn, Sr, Se) oxides on the oxidation of UO2 to U3O8 were investigated by TG/DSC, XRD, FT-IR and Raman. It was found that the oxidation of UO2 to U3O8 went through two stages: UO2→U3O7; U3O7→U3O8. Doping M oxide in UO2 could not change the two-step mechanism, and significantly inhibited the formation of U3O8. The final products of CeO2 and SrO-doped UO2 oxidation contained 20% U3O7 and 47% U3O7, respectively. The doping of M oxide increased the onset oxidation temperature of the two oxidation stages of UO2 by 5–65 °C. In addition, the kinetic mechanism of UO2 oxidation was investigated and found that the first and second oxidation stages were controlled by 1st order reaction or nucleation and growth, and 2nd order reaction, respectively. The doping of M oxide significantly affected the kinetic mechanism of the first stage.

Countercurrent chemical looping for enhanced methane reforming with complete conversion and inherent CO[formula omitted] separation

Methane reforming is a widely applied chemical process for the production of hydrogen and syngas. It can play an important role in the energy transition, allowing for the production of so called blue hydrogen, or in the processing of biogas for renewable fuel and fertiliser production. This work describes and demonstrates a novel countercurrent chemical looping reforming process, which offers a new mode of reforming with complete conversion of methane, inherent separation of pure CO2, and flexibility in the choice of oxidant allowing for hydrogen or syngas production. The packed-bed chemical-looping reactor operates by storing the favourable oxygen chemical potential inclines of the alternating countercurrent flows using the unique properties of non-stoichiometric oxides. The improvement in chemical equilibrium limitations are illustrated using an analysis of an idealised countercurrent membrane reactor. The concept is experimentally demonstrated in a dry reforming process using the non-stoichiometric oxide CeO2−δ at a temperature of 1203K. The results show complete oxidation of CH4 to CO2 and H2O in the reduction step, and a cumulative CO2-to-CO molar conversion of 86 % during oxidation.

Constructing Heterointerfaces in Dual-Phase High-Entropy Oxides to Boost O2 Activation and SO2 Resistance for Mercury Removal in Flue Gas.

The low O2 activation ability at low temperatures and SO2 poisoning are challenges for metal oxide catalysts in the application of Hg0 removal in flue gas. A novel high-entropy fluorite oxide (MgAlMnCo)CeO2 (Co-HEO) with the second phase of spinel is synthesized by the microwave hydrothermal method for the first time. A high efficiency of Hg0 removal (close to 100%) is achieved by Co-HEO catalytic oxidation at temperatures as low as 100 °C and in the atmosphere of 145 μg m-3 Hg0 at a high GHSV (gas hourly space velocity) of 95,000 h-1. According to O2-TPD and in situ FT-IR, this extremely superior catalytic oxidation performance at low temperatures originates from the activation ability of Co-HEO to transform O2 into superoxide and peroxide, which is promoted by point defects induced from the spinel/fluorite heterointerfaces. Meanwhile, SO2 resistance of Co-HEO for Hg0 removal is also improved up to 2000 ppm due to the high-entropy-stabilized structure, construction of heterointerfaces, and synergistic effect of the multicomponents for inhibiting the oxidation of SO2 to surface sulfate. The design strategy of the dual-phase high-entropy material launches a new route for metal oxides in the application of catalytic oxidation and SO2 resistance.

A novel approach to tailoring the microstructure and electrophysical properties of Ni/GDC-based anodes by combining 3D-inkjet printing and layer-by-layer laser treatment

This work proposes an original method for tailoring the microstructure and electrical properties of Ni/GDC anodes by using 3D inkjet printing of high-viscosity functional compositions with intermediate laser treatment of each layer after each printing pass. Based on a mixture of highly dispersed oxides NiO and CeO2 doped with gadolinium (GDC), paste formulations for 3D inkjet printing have been developed. The effects of 3D printing and laser treatment conditions on the porosity and shrinkage ratio of the NiO/GDC anodes during sintering were investigated. The reduction of the anode support workpieces to produce Ni/GDC cermet was carried out and the effect of laser exposure on the morphology and electrical characteristics of the resulting samples was studied. It was found that an increase in the laser exposure values during layer-by-layer laser treatment of printing compositions leads to a two-fold increase in the porosity of the solid oxide fuel cell components, an increase in the average pore size from 0.2 to 0.3 to 2–5 μm, and to a five-fold decrease in the sintering shrinkage ratio. It was also found that the electrical conductivity of the Ni/GDC cermet, produced by the reduction of the laser treated NiO/GDC, increased by 5–10 times as the laser exposure values increased. The influence mechanism of the layer-by-layer laser treatment of the original NiO/GDC samples on the electrical conductivity of their reduced counterparts, Ni/GDC cermet anodes, has been proposed. An increase in the electrical conductivity was shown to be due to in situ reduction of NiO, partial sintering of Ni nanoparticles and the formation of a percolation network. This new method of hybrid 3D printing opens up great prospects for tailoring the morphological and electrical characteristics of SOFC anode supports.

Insight into the promotional effect of Ce doped in (FeCoNiCrMn)3O4 high entropy oxides for solvent-free aerobic oxidation of benzyl alcohol

It is desired but challenging to develop a non-noble metal catalyst for the selective oxidation of benzyl alcohol with O2 under solvent-free conditions. Herein, a series of Ce-doped high entropy oxides (Ce/HEOs) were prepared via co-precipitation and subsequent thermal treatment method. It was found that, the doping of Ce could remarkably promote the catalytic activity for selective oxidation of benzyl alcohol to benzaldehyde. The improved activity was ascribed to the good distribution of active Ce species, the increased oxygen vacancies, and the synergistic effect between CeO2 and high entropy oxides (HEOs). In addition, the surface oxygen of Ce/HEOs towards Ce displayed stronger reducibility compared to that of bare CeO2, endowing it stronger deprotonation ability towards benzyl alcohol during the reaction. The prepared catalyst exhibited satisfactory reusability and stability owing to the entropy-stabilized effect of HEOs and the interaction between CeO2 and HEOs, and negligible loss in catalytic activity was observed after seven runs. Besides, DFT calculations disclosed that, with the doping of Ce, the Ce/HEOs catalyst possessed stronger adsorption ability towards benzyl alcohol, and lower free energy was required for the rate-determining step during the whole oxidative reaction. This work gave some insights into the promotional effect of Ce doped into high entropy oxides for the solvent-free catalytic oxidation of benzyl alcohol.

Promising doped and co-doped CeO2 and TiO2 oxides for optoelectronic applications: First principles approach

Wide-gap oxides are promising materials for optoelectronic applications due to their exceptional optical, electronic, and structural properties. This paper explores the impact of doping and co-doping on the structural, electronic, magnetic, and optical properties of CeO2 and TiO2 using a first-principles approach based on the full potential linearized augmented plane wave (FP-LAPW) method within the framework of density functional theory (DFT). The results show that doping and co-doping lead to a significant change in the lattice parameters, which is of paramount importance as it affects the fundamental properties of the compounds. The optimized structural parameters authenticate the stability of the ferromagnetic phases, and the formation energies justify the stability conditions of the compounds. Furthermore, a half-metallic character with an indirect band gap (spin-up) and semiconductor features is achieved for doping and co-doping models based on CeO2 and TiO2, respectively. There is no significant difference between single doping and co-doping in terms of total magnetic moment values since both single doping and co-doping compounds contribute a total magnetic moment of 2μB each. In addition, after the doping process, many optical parameters, including the absorption coefficient and dielectric constants, become much better, resulting in amplified absorption peaks in the visible and UV areas. These findings suggest that compounds exhibit interesting features for spintronic and optoelectronic technologies.

The calcination temperature effect on CeO2 catalytic activity for soot oxidation: a combined experimental and theoretical approach

The catalytic efficiency of CeO2 in soot oxidation was significantly affected by its grain morphology and calcination temperature.