Effect Of Ce Doping Research Articles

Preparation and characterization of Ce doped ZnO nanomaterial for photocatalytic and biological applications

Cerium doped zinc oxide (CZO) nanomaterials have been synthesized by the sol–gel combustion method. The effect of Ce doping (up to 5 mol%) on the structural, morphological, optical and photoluminescence properties has been investigated and the applications of CZO in photocatalytic and antibacterial studies were also assessed. X-ray diffraction analysis revealed that the CZO nanomaterials have the hexagonal wurtzite structure. The maximum crystallite size of 84 nm was obtained for the 1 mol% Ce doped nanomaterial. The morphology of the CZO powder was gradually affected by the Ce doping concentration. Element mapping using energy dispersive X-ray spectroscopy showed the uniform distribution of Ce atoms in the ZnO, but higher resolution nano-scanning Auger microscopy measurements revealed enhanced Ce concentration in nanoparticles occurring in the doped material. The absorption spectra were calculated from reflection measurements using the Kubelka-Munk function and showed strong absorbance below 410 nm. The optical bandgap slightly varied around 3.20 eV for the different Ce doping concentrations. Photoluminescence consisted of a broad emission band centered at 635 nm having a clear blue shift as the Ce concentration increased. A photocatalytic study was done by means of methylene blue as a dye in UV light. The doped oxide is also an antibacterial/antifungal agent and its efficiency has been measured against bacteria (Staphylococcus aureus and Escherichia coli) and yeasts (Eremothecium ashbyii and Nadsonia fulvescens).

Effects of Ce Doping on the Photocatalytic and Electrochemical Performance of Nickel Hydroxide Nanostructures

Ni(OH)2 doped with cerium cations was synthesized by a hydrothermal method and its electrochemical, photoelectrochemical and photocatalytic behavior was determined by the corresponding suitable techniques. Ni(OH)2 films doped with different Ce proportions were evaluated in a KOH support electrolyte solution by cyclic voltammetry. Scan-rate dependent voltammograms displayed pseudo-capacitive behavior while the charge transfer resistance of Ce-doped samples was determined through electrochemical impedance spectroscopy. The calculated charge transfer resistance value was 132 Ω for Ni(OH)2 containing 350 μmoles of Ce. Chronoamperometry under intermittent UV light was employed to measure the photo-response of nanomaterials. The experimental results indicated that the photocurrent of Ni(OH)2 containing 350 µmoles of Ce was ten times greater than that of pure Ni(OH)2. Photocatalytic activity of the powders was demonstrated under UV light irradiation accomplishing 83% of methyl orange degradation after 140 min of reaction with pseudo-first-order kinetics and the calculated degradation rate constant was 0.0125 min− 1. The results evidenced the electrochemical, photoelectrochemical and photocatalytic activity of the synthesized materials, which sets them as suitable materials for a wide range of promising photo-based applications.

Effects of Ce doping on the Fenton-like reactivity of Cu-based catalyst to the fluconazole

In order to fully exploit the potential of Cu-based Fenton systems, Ce was utilized to modify the Cu-based catalysts through one-pot synthesis. A typical antifungal drug, fluconazole (FLC), was selected as the target pollutant to evaluate the reactivity of as-synthetic Cu-Ce bimetallic catalysts. Evaluation test results indicated Ce5%CuOy bimetallic materials exhibit the most excellent catalytic activity. Compared to copper monometallic catalyst, its fluconazole degradation efficiency and TOC removal rate are increased by 20% and 15%, respectively. Ce5%CuOy also possess wide pH applicability (3.0–9.0) and maintain high activity after 4 runs. Radical quenching experiments and fluorescent probes tests showed that hydroxyl radicals (OH) played a dominant role in the degradation of FLC. The various characterization illustrated that Ce doping (2.5–5 at%) significantly improved the properties related to catalytic activity, such as morphology Cu(I) ratio, specific surface area, interface electron transfer rate and unpaired electron content. In particular, the increase in the unpaired electron content and Cu(I) ratio endow more electron-rich centers and active sites on the composite surface, which facilitates the H2O2 to receive electrons and decompose into OH. Finally, the degradation intermediates during fluconazole oxidation were identified by LC/MC.

Effect of Ce Doping on Hydrothermal Stability of Cu-SAPO-18 in the Selective Catalytic Reduction of NO with NH3

The Ce-Cu-SAPO-18 samples were prepared by the ion exchange method. Physicochemical properties of the samples were systematically characterized by a number of analytical techniques, and Ce doping and hydrothermal temperature effects on NH3-SCR activity of Cu-SAPO-18 were also investigated. The results show that doping of Ce increased NH3-SCR activity and hydrothermal stability of the Cu-SAPO-18 sample. After Ce doping, a more amount of the isolated Cu2+ ions entered the D6R and the catalyst structure was more stable. The structure and catalytic activity of Ce-Cu-SAPO-18 remained almost intact after hydrothermal aging at 650 °C. After hydrothermal aging at 850 °C, however, the structure of Ce-Cu-SAPO-18 was greatly destroyed, and its catalytic activity declined remarkably. The high-temperature hydrothermal aging treatment led to decreases in amount of the isolated Cu2+ ions and acidic sites, destroying in the zeolitic structure, and drop in NH3-SCR activity.

Effect of Ce Doping on Catalytic Performance of Cu/TiO2 for CO Oxidation

CO is toxic and detrimental to human beings and the atmosphere. The presence of CO has become one of the important indicators for evaluating ambient air quality. Iron and steel sintering generate large amounts of flue gas emissions containing approximately 1% CO, which has become an important factor restricting the improvement of air quality in steel cities. The catalytic oxidation method is the simplest and most effective method for CO emission control. In this work, a series of CuxCey/TiO2 catalysts with different Ce doping levels were prepared by a one-step impregnation method and subsequently tested for catalytic CO oxidation. The Cu0.5Ce0.5/TiO2 sample has the best catalytic activity under the conditions of 1% CO and 10% H2O. The catalysts were next characterized by XRD, BET, TEM, H2-TPR, XPS and in-situ DRIFTS methods. The characterization results show that Ce doping promotes the dispersion of copper species on the catalyst surface and improve the redox performance of the catalyst. The results of in-situ experiments showed that both Cu/TiO2 and Cu0.5Ce0.5/TiO2 catalysts followed Mars and van Krevelen mechanism, and Ce doping enhanced the adsorption and activation of oxygen, thus improving the low-temperature reaction activity of the catalysts.

Ce-doping effect on modulation of spin-exchange interaction and dielectric behaviour of nanostructured LaFeO3 orthoferrites

In present attempt, Ce-doped LaFeO3 (LCFO) system is explored as single phase room temperature multiferroics (MFs). Nano-crystalline LCFO system with various compositions of Ce [La1-xCexFeO3 (0 ≤ x ≤ 0.1)] are synthesized by microwave-assisted gel combustion method. Detailed Rietveld analysis of X-ray diffraction data revealed that the systems retain distorted orthorhombic phase with space group Pbmn for x < 0.10; However, impurity phase related to CeO2 is detected for x = 0.1 indicates solid solubility limit of Ce in LFO is x ≤ 0.08. New phonon mode related to Ce translational vibration with several kinks above 300 cm−1 are detected in Fourier transform infrared spectra; is a clear indication of structural modification of LFO by Ce. Enhanced magnetization with Ce doping content are attributed to spin exchange interaction Ce3+-O-Fe3+ and Fe3+-O-Fe3+. M-H curves exhibit partial ferromagnetic nature with G-type antiparallel spin arrangement of LCFO. Temperature driven dielectric and magnetic behaviour exhibit transition near Néel temperature evidence for magneto-dielectric coupling in LCFO systems. Remarkable enhancement in the magnetization, coercivity, and remanant magnetization with reduction in dielectric constant, loss and leakage current of LFO by Ce-doping suggests that LCFO ferrites are promising materials as room temperature multiferroic.

Structural and optical properties of Ce doped BiFeO 3 nanoparticles via sol–gel method

The effect of Ce doping on the structural and optical properties of BiFeO3 nanoparticles via sol–gel method is reported. All samples were a pure phase with perovskite structure. The EDX results show the doped samples contain Bi, Fe, O and Ce elements. The vibrational properties of samples were studied using Raman spectroscopy. Photoluminescence shows an intense peak at 398 nm, the peak strength enhanced greatly and had redshift with the increase of Ce doping concentration. UV–vis results show the samples have a broad absorption band in the range of 500–600 nm. The bandgaps decrease with the concentration increase of Ce doping. It indicates the as-prepared BiFeO3 can be used as visible light catalyst.

Effect of Ce Doping on the Structure and Chemical Stability of Nano-α-Fe2O3.

Ce-doped nano-α-Fe2O3 was successfully synthesized via the hydrothermal method. The properties of the prepared particles were studied by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and electrochemical methods. It was found that the Ce element can be doped into the α-Fe2O3 lattice resulting in lattice distortion, which can refine the grain and improve the crystal surface’s integrity significantly. In addition, doping of Ce element can shorten the Fe–O bond length in the α-Fe2O3 crystal, cause a blue shift of the stretching vibration band, enhance binding energy of Fe–O and the chemical stability of the α-Fe2O3 crystal.

Effect of phase transition on room temperature ferromagnetism in cerium doped ZnS nanorods

The effects of Ce doping on the structure, optical, oxidation, thermal and magnetic properties of ZnS:Ce nanorods synthesized by a chemical co-precipitation method were reported. The crystalline phase transformation from cubic to hexagonal structure was observed upon doping ZnS with Ce. Magnetic measurements showed the existence of room temperature ferromagnetism in Ce-doped ZnS nanorods. X-ray photoelectron spectroscopic (XPS) measurements provided evidence for Zn—S bonds and oxidation state of Ce in the near-surface region. Raman spectrum provided evidence for the presence of defects as well as hexagonal structure of 5 wt.% Ce doped ZnS nanorods. Ce substitution induced shape evolution was studied by using TEM. DRS spectra further validated the incorporation of Ce3+ ions. The present study reveals that Ce doped ZnS nanorods may find applications in spintronic devices.

A significant effect of Ce-doping on key characteristics of NiO thin films for optoelectronics facilely fabricated by spin coater

Abstract NiO has been found to have excellent physical properties which are crucial for several significant electro-optical devices. Herein, we have designed and fabricated high-quality films of NiO with various concentrations of Ce and studied their key properties. X-ray diffraction (XRD) study confirmed the cubic phase, good crystallinity and growth direction along (111) plane in the prepared samples. The crystallite size was noticed in the range of 13–30 nm. For confirming the presence of Ce doping and its homogeneity in NiO films the EDX/SEM mapping was carried out. AFM study provided the topographic information in terms of size of the grains and roughness of all films. The grown films were found to be 70–80% optically transparent in the whole testing region. Optical energy gap was found to expand from 3.60 to 3.68 eV owing to Ce-doping. The refractive index value was noticed to be in the range from 1.7 to 2.7. The n2 and χ ( 3 ) values for pure and Ce-doped NiO films varied from 2 × 10−10 to 1.4 × 10−11 and 1 × 10−12 to 1.1 × 10−11 esu, respectively. Obtained results indicated that Ce has strong influence on opto-nonlinear characteristics of NiO films and proposed their application in the opto-nonlinear devices.

Defect assisted improved room temperature ferromagnetism in Ce doped SnO2 nanoparticles

In the present work, pure and Ce doped SnO2 have been prepared via sol-gel method and the effect of Ce doping on the structural, optical and magnetic properties of SnO2 are studied systematically. A detailed structural analysis has been carried out by X-ray diffraction (XRD), field emission scanning microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy, Raman scattering, X-ray photoelectron spectroscopy (XPS). These studies reveal that pure and Ce doped SnO2 NPs have a polycrystalline single phase tetragonal rutile structure without any detectable impurity phases and most of the dopant ions occupy the lattice site into the host structure of SnO2. The core level XPS spectrum of Ce 3d reveals that most of the Ce ions are in 3+ valence state. Simulated O K-edge based soft X-ray absorption analysis, high resolution O 1s XPS results and photoluminescence study reveal that oxygen vacancies are generated in the doped samples. Band gap of SnO2 is found to decrease with increase in Ce content. Magnetic measurements show that all the Ce doped samples clearly display the room temperature ferromagnetic behavior while pure SnO2 shows diamagnetic nature. Magnetic parameters have been determined from the fitted M-H loops and transition from diamagnetic to ferromagnetic is observed when Ce ions are doped into SnO2 structure.

Effect of rare element Ce doping concentration on resistive switching of HfOx film

The switching characteristics of rare element Ce-doped HfOx films were investigated. The effect of Ce doping on oxygen defects was analyzed by X-ray photoelectron spectroscopy (XPS) and first-principle calculations. The variations of valence state of Ce and oxygen vacancies with the increase of Ce doping concentration were demonstrated. Although Ce doping increased dopants-induced oxygen vacancies in HfOx film, the density of oxygen vacancies decreased as the doping concentration increased. Besides, the introduction of Ce dopants enlarged the difference in electronegativity of Hf and O which made it harder for O to escape from HfOx film under voltage. Hence the switching behaviors of Ce-doped HfOx film were affected by multiple factors and can be effectively improved with an appropriate doping concentration (4.3%). A physical model based on the formation and rupture of conductive filaments was proposed to clarify the switching behavior of Ce-doped HfOx samples.

Impact of Ce content on cubic phase cerium–cadmium oxide (Ce–CdO) nanoparticles and its n-CeCdO/p-Si junction diodes

Microwave irradiation method was adopted to synthesize Ce doped CdO nanoparticles. The n-CeCdO/p-Si junction diode was fabricated and it’s parameters have been studied at different doping concentrations (0, 5, 10, and 15 wt%) of Ce. The Ce doping effect was analyzed by various characterization techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray photo electron spectroscopy (XPS), ultra violet–visible spectroscopy (UV–Vis) and DC conductivity (I–V) studies. From XRD analysis, the Ce–CdO nanoparticles depicted a crystalline nature and showed the cubic phase. The crystallite size of the samples varied from 18.72 to 14.68 nm. TEM images reveal that the Ce–CdO nanoparticles have nail-like structure. The presence of the elements Ce, Cd and O were confirmed by EDX and XPS studies. The optical bandgap value decreases with the increasing doping concentration and the minimum band gap energy of 2.70 eV is obtained for 15 wt% Ce–CdO sample. I–V curve represents the semiconducting behavior of Ce–CdO nanoparticles. Variation of current in Ce doped CdO nanoparticles exhibits linear response to applied voltage. The diode behavior was studied under darkness and illumination environment. The major diode parameters, ideality factor and barrier height of n-CeCdO/p-Si junction diode were examined using J–V method.

Effect of Ce doping on the structure and optical properties of HfO2 films by the Pechini-type sol–gel method

HfO2 and Ce-doped HfO2 thin films were deposited by the spin coating of Pechini-type sol–gel solutions on silica-fused substrates. The effect of Ce doping on the structure and optical properties of the HfO2 thin films were studied. The microstructure analysis of the resulting films revealed that the insertion of Ce ions into the HfO2 lattice caused a phase transformation from the monoclinic to the metastable tetragonal t′ form. The surface morphology studies revealed the homogeneous deposition of HfO2 and Ce-doped HfO2, with thicknesses ranging from 515 to 590 nm, formed by the aggregation of spherical particles with sizes <10 nm. X-ray photoelectron spectroscopy revealed the insertion of both Ce3+ and Ce4+ ions in the structure of the Ce-doped HfO2. Although all films were optically transparent, the presence of Ce3+ ions (oxygen vacancies) induced color centers related to the yellowish coloration of the Ce-doped HfO2 films and a red-shift of the optical band gap from 5.67 to 4.02 eV.

Effect of Ce doping on crystalline orientation, microstructure, dielectric and ferroelectric properties of (100)-oriented PCZT thin films via sol–gel method

Pb1.2−xCexZr0.52Ti0.48O3 (PCZT, x = 0%, 0.1%, 0.5%, 1%, 2% and 3%) thin films with the thickness of about 1 µm were fabricated by sol–gel process and traditional annealing process on Pt/Ti/SiO2/Si substrates to investigate the effect of cerium doping on crystalline orientation, microstructure and electric properties of the samples. (100)-oriented Pb1.2−xCexZr0.52Ti0.48O3 films were obtained for all x values. The results of Scanning electron microscopy (SEM) revealed that the 0%, 0.1%, 0.5%, and 1% cerium doped Pb1.2−xCexZr0.52Ti0.48O3 films have a dense columnar perovskite structure. The maximum dielectric constant and remnant polarization were obtained for 0.1% Ce-doped film.

Upgrading of vacuum residue with chemical looping partial oxidation over Ce doped Fe2O3

Partial oxidation provides a promising method for upgrading of heavy oil. In this study, a series of Ce doped Fe2O3 materials were prepared and applied for partial oxidation of vacuum residue. The effect of Ce doping on the physicochemical properties of Fe2O3 was recognized through a series of characterization techniques. Some Fe in Fe2O3 structure were substituted by Ce to form solid solution, resulting in increase of specific surface area and oxygen vacancy concentration. The partial oxidation of vacuum residue showed that Ce doping to Fe2O3 could increase the heavy oil conversion, yields of gasoline and diesel, which are attributed to the large specific surface area and increased oxygen vacancy concentration. Based on the partial oxidation performance of Ce doped Fe2O3, a chemical looping for upgrading of vacuum residue using FeCe-1 as oxygen carrier was proposed. The heavy oil conversion, yield of gasoline and diesel remain stable under chemical looping process.

Structural, optical and electrical properties of a Schottky diode fabricated on Ce doped ZnO nanorods grown using a two step chemical bath deposition

Schottky diodes based on pure and Ce doped ZnO nanorods with Ce at% from 0.0 to 10.0 were fabricated using a chemical bath deposition technique. The effect of Ce doping on structural, optical and electrical properties was studied. X-ray diffraction spectroscopy and field emission scanning electron microscopy were used to study the crystalline structure and surface morphology, respectively. Raman spectroscopy at room temperature revealed that the dominant E2(high) peaks of Ce doped ZnO nanorods were red shifted compared to those in undoped ZnO. Room temperature photoluminescence spectroscopy of as-synthesized pure and Ce-doped ZnO nanorods showed that the UV emission was also red shifted with Ce doping enhancing the green-yellow emission compared to undoped ZnO nanorods. The optical band gap of pure and Ce doped ZnO nanorods were obtained from UV–vis results. Moreover, the I-V characteristics of a fabricated Schottky diodes revealed that the rectification behaviour of the diodes was improved by Ce doping. The maximum rectification was obtained at 10.0 at% Ce with ideality factor of 1.34 and barrier height of 0.856 eV.

Effect of Ce doping on the resistance of Na over V2O5-WO3/TiO2 SCR catalysts

Enhanced performance of Ce doping on the catalytic activity of V2O5-WO3/TiO2 catalysts and its resistance properties to Na poisoning have been investigated in the research. Different Na species (NaCl and Na2O) were deposited on CeO2-V2O5-WO3/TiO2 catalysts by impregnation method. The results presented that CeO2-V2O5-WO3/TiO2 catalysts exhibited a higher NH3-SCR activity and better Na resistance than the V2O5-WO3/TiO2 catalyst, and its poisoning resistance to Na2O is more superior than to NaCl, caused by more acid sites over the 10%CeO2-V2O5-WO3/TiO2 (Ce10VWTi) catalyst, which indicated that the poisoning resistance of Na2O on Ce10VWTi catalysts is higher than that of NaCl. Combined with the characterization results, the dopant of Ce could enhance the surface chemisorbed oxygen on the Na poisoning V2O5-WO3/TiO2 catalysts, facilitate the redox cycle, and increase the intensity of acid sites due to the newly formed Brønsted acid sites stemmed from Ce3+−NH4+, thereby promoting catalytic activity and Na poisoning resistance.

Alkali resistance promotion of Ce-doped vanadium-titanic-based NH3-SCR catalysts

The effect of K deactivation on V2O5/WO3-TiO2 and Ce-doped V2O5/WO3-TiO2 catalysts in the selective catalytic reduction (SCR) of NOx by NH3 was studied. Ce-doped V2O5/WO3-TiO2 showed significantly higher resistance to K deactivation than V2O5/WO3-TiO2. Ce-doped V2O5/WO3-TiO2 with K/V=4 (molar ratio) showed 90% NOx conversion at 350°C, whereas in this case V2O5/WO3-TiO2 showed no activity. The fresh and K-poisoned V2O5/WO3-TiO2 and Ce-doped V2O5/WO3-TiO2 catalysts were investigated by means of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), NH3-temperature progress decomposition (NH3-TPD), X-ray photoelectron spectroscopy (XPS) and H2-temperature program reduction (H2-TPR). The effect of Ce doping on the improving resistance to K of V2O5/WO3-TiO2were discussed.

Effects of Ce doping and humidity on UV sensing properties of electrospun ZnO nanofibers

Pure ZnO and Ce-doped ZnO nanofibers were synthesized via electrospinning-calcination technique. The morphology, composition, structure, humidity sensing and photoelectric properties were characterized. The field-effect curves showed that a single pure ZnO nanofiber is an n-type semiconductor and an individual Ce-ZnO nanofiber is a p-type semiconductor. The Ce doping and humidity have strong influence on the UV sensing properties of ZnO-based nanofibers. In the dark, the responses [(IVarious RH − I43% RH)/I43% RH] of pure ZnO increased gradually with the increase of humidity, while the responses of Ce-doped ZnO nanofibers decreased. When exposed to UV radiation, the response of pure ZnO nanofibers decreased with increasing humidity, while that of Ce-doped ZnO increased. And the highest responses are around 88.44 and 683.67 at 97% humidity for pure ZnO and Ce-ZnO nanofibers under UV irradiation. In addition, the UV response of Ce-ZnO with good stability and repeatability increases by two orders of magnitude than that of pure ZnO. The sensing mechanism relevant to oxygen and water-related conduction was discussed briefly. These results exhibit that the application prospects of p-type Ce-ZnO nanofibers are promising in the field of photoelectric devices.