Effect of Ce-doping on catalysts derived from hydrotalcite-like precursors for COS hydrolysis

In order to investigate the effect of Ce-doping on the catalysts derived from hydrotalcite-like precursors for carbonyl sulfide(COS) hydrolysis,a series of Zn-Ni-Al-Ce hydrotalcite-like compounds were prepared by co-precipitation method and the catalytic activity of their derived composite oxides were studied at 50 oC.The effect on the structural properties caused by Ce doping was studied by the X-ray diffractometer(XRD),scanning electron microscopy(SEM) and energy dispersive spectrometer(EDS).The catalytic activities results showed that addition of Ce enhanced the catalytic activities significantly,but excessive Ce-doping had a negative effect on COS hydrolysis.XRD,SEM and EDS results illustrated that,compared with the Ce-free sample,the particle size of oxide solids decreased and the degree of dispersion increased due to Ce doping.

STM and STS investigations of Ce-doped TiO_2 nanoparticles

Ce-doped titanium oxide nanoparticles were investigated in the paper. The surface structures of undoped and Ce-doped TiO2 nanoparticles were observed by scanning tunneling microscopy （STM）. The experimental results of scanning tunneling spectroscopy （STS） show that the surface electronic structures of TiO2 nanoparticles are modified by introducing new electronic states in the surface band gap through cerium ion doping. The results are discussed in terms of the influence of doping concentration on the surface band gap of TiO2.

Preparation and Spectroscopic Properties of Ce-Doped High-Silica Glass

In order to develop a novel electric light source, the doped high-silica glass was studied on the preparation and spectroscopic properties. ne porous glasses were made firstly and were then immersed in the solution containing Ce ion. Thereafter, the high-silica glasses containing Ce ion were prepared by sintering the porous preform. The spectroscopic properties were studied before and after heath treatment in H-2. The experimental results indicate that the suitable temperature schedules are the most important to prepare doped high-silica glass. The study of the spectra shows that Ce ion can be reduced to low valence state when it is heat-treated in H-2. It can be used to adjust the UV cut-off wavelength of high-silica glass by changing the valence state of Ce ion.

Study on Desulfurization Efficiency and Products of Ce-Doped Nanosized ZnO Desulfurizer at Ambient Temperature

Ce-doped nanosized ZnO desulfurizer was prepared by homogeneous precipitation,and its desulfurization efficiency at ambient temperature was investigated through dynamic experiments.The results showed that the desulfurization activity of nanosized Ce-ZnO had improved greatly,compared to nanosized ZnO desulfurizer.Nanosized Ce-ZnO desulfurizer was characterized by XRD,TPD-MS,XPS,and TEM.The research results indicated that doping Ce decreased the particle size of the nanosized ZnO desulfurizer and ZnS was the principal desulfurization product.There were adsorption complexes of HS and S on the surface of desulfurizer as well.Only a small amount of vapor appeared in the tail gas on the condition of meeting the precision of desulfurization.

Selective catalytic oxidation of NO with O_2 over Ce-doped MnO_x/TiO_2 catalysts

A series of Ce-doped MnOx/TiO2 catalysts were prepared by impregnation method and used for catalytic oxidation of NO in the presence of excess O2. The sample with the Ce doping concentration of Ce/Mn=l/3 and calcined at 300 ℃ shows a superior activity for NO oxidation to NO2. On Ce（1）Mn（3）Ti catalyst, 58% NO conversion was obtained at 200 ℃ and 85% NO conversion at 250 ℃ with a GHSV of 41000 h-1, which was much higher than that over MnOx/TiO2 catalyst （48% at 250 ℃）. Characterization results implied that the higher activity of Ce（1）Mn（3）Ti could be attributed to the enrichment of well-dispersed MnO2 on the surface and the abundance of Mn3＋ and Zi3＋ species. The addition of Ce into MnO2/TiO2 could improve oxygen storage capacity and facilitate oxygen mobility of the catalyst as shown by PL and ESR, so that its activity for NO oxidation could be enhanced. The effect of H2O and SO2 on the catalyst activity was also investigated.

Ce-Doped Smart Adsorbentswith Photoresponsive Molecular Switches for Selective Adsorption and Efficient Desorption

Achieving efficient adsorption and desorption processes by controllably tuning the properties of adsorbents at different technical stages is extremely attractive.However,it is difficult for traditional adsorbents to reach the target because of their fixed active sites.Herein,we report on the fabrication of a smart adsorbent,which was achieved by introducing photoresponsive azobenzene derivatives with cis/trans isomers to Ce-doped mesoporous silica.These photoresponsive groups serve as “molecular switches”by sheltering and exposing active sites,leading to efficient adsorption and desorption.Ce is also doped to provide additional active sites in order to enhance the adsorption performance.The results show that the cis isomers effectively shelter the active sites,leading to the selective adsorption of methylene blue(MB)over brilliant blue(BB),while the trans isomers completely expose the active sites,resulting in the convenient release of the adsorbates.Both selective adsorption and efficient desorption can be realized controllably by these smart adsorbents through photostimulation.Moreover,the performance of the obtained materials is well maintained after five cycles.

Synthesis and Optical Properties of Ce-doped ZnO

ZnO nanorods were synthesized using the sol-gel method, and the effects of annealing temperature and Ce doping on the morphologies and optical properties of ZnO nanostructures were investigated in detail. The XRD measurements showed that the as-synthesized ZnO nanostructures had a hexagonal wurtzite structure. SEM images showed that uniform nanorods formed at 900 °C. Photoluminescence measurements showed an ultraviolet emission peak and a relatively broad visible light emission peak for the samples sintered at different temperatures. The UV emission peak bathochromically shifted when the annealing temperature rose from 850 to 1000 °C. Ce doping decreased the synthesized temperature of the ZnO nanorods to 500 °C, and the UV peaks hypsochromically shifted.

Structure and Electric Conductivity of Ce-doped Bi_2O_3 Electrolyte Synthesized by Reverse Titration Chemical Coprecipitation

Ce-doped Bi2O3 nanopowders were prepared by reverse titration chemical coprecipitation from Bi^3＋and Ce^（4＋）containing aqueous solution.Techniques of X-ray diffraction（XRD）,transmission electron microscopic（TEM）and Fourier transform infrared spectroscopy（FTIR）were employed to characterize the as-synthesized materials.The XRD patterns indicated that the peaks can be easily indexed toβ-Bi2O3 and no diffraction peaks of Ce or other impurity phases were detected in the prepared samples.The calculated average crystalline size decreased from 31.72 to 11.96 nm when the Ce content increased from 1 wt%to 10 wt%.The morphology changed from flake-like into the spherical-like with increase in Ce content.The electric conductivity of Ce-doped Bi2O3 electrolyte was also investigated by two probe DC method.Conductivity analysis exhibited that the rate of conductivity increased with increasing Ce^2＋ratio,when the Ce concentration was up to 5 wt%,the as-synthesized Ce-doped Bi2O3 electrolyte showed the maximum value of conductivity（0.295 S？cm^（–1））.

Enhanced photocatalytic degradation of 4-nitrophenol using polyacrylamide assisted Ce-doped YMnO_(3) nanoparticles

This research article mainly reports on the precise structural,optical,and photocatalytic properties of cerium(Ce)-substituted yttrium manganite(YMnO_(3))nanoparticles synthesized by the polyacrylamide gel method.The characteristics of YMnO_(3)were investigated by the substitution of Ce into the Y site at various molar percentages.The Raman and X-ray diffraction(XRD)analyses confirmed the pure phase of hexagonal YMnO_(3),supported by the Rietveld refinement.The microstructural studies indicate inhomogeneous and irregular particle distribution.The X-ray photoelectron spectroscopy(XPS)results show the presence of two ionic states of Mn and Ce along with Y^(3+)state and oxygen vacancies.Extensive optical exploration using photoluminescence(PL)spectroscopy and UV-Vis-NIR analysis indicates that the intensity of absorption peak increases in the visible region,while the bandgap decreases from 1.42 to1.30 eV with the Ce ion doping(5 mol%-15 mol%).Photocatalytic properties of the polycrystalline nanoparticles were investigated by degradation of the pollutant 4-nitrophenol.The process of amplified photocatalysis process was elucidated by the lowered bandgap and rate of charge carrier recombination.It can be conjugated from this study that the synthesized nanoparticles may be employed as highly efficient(92.8%)visible light-triggered photocatalysts in a variety of real-world applications.

Influence of cerium ions on the anatase-rutile phase transition of TiO_2 prepared by sol-gel auto-igniting synthesis

The anatase-rutile phase transformation of TiO_2 doped cerium up to 5 molpercent was studied by X-ray diffraction and X-ray photoelectron spectroscopy. The samples wereprepared by sol-gel auto-igniting synthesis process from a TiO(NO_3)_2-Ce(NO_3)_2-NH_4NO_3-citricacid complex compound system. The combusted amorphous powders were calcined at differenttemperatures. Significant structural changes were observed during the various stages of the phasetransformation. It was concluded that at low dopant contents, cerium ions were incorporated into theTiO_2 structure, and the anatase phase was stabilized; but at larger amounts, part of the dopantwas segregated on the surface of TiO_2 and the rutile formation was accelerated at elevatedcalcination temperature.

Synthesis of cerium-doped MCM-48 molecular sieves and its catalytic performance for selective oxidation of cyclohexane

Cerium-doped MCM-48 molecular sieves were synthesized hydrothermally and characterized by X-ray diffraction, nitrogen adsorption, transmission electron microscope, FT-IR spectroscopy, UV-visible spectroscopy, and Raman spectroscopy. The results showed that all the samples held the structure of MCM-48, and Ce could enter the framework of MCM-48. However, when Ce/Si molar ratio in the sampies was high （0.04 or 0.059）, there were CeO2 crystallites as secondary phase in the extraframework of MCM-48. Ce-doped MCM-48 was a very efficient catalyst for the oxidation of cyclohexane in a solvent-free system with oxygen as an oxidant. In the conditions of 0.5 MPa 02 and 413 K for 5 h, the conversion of cyclohexane was 8.1% over Ce-MCM-48-0.02, the total selectivity of cyclohexanol and cyclohaxnone was 98.7%. With an increase of Ce content, the conversion of cyclohexane and the selectivity to cyclohexanol decreased somewhat, but the selectivity to cyclohexanone increased.

Structural and Electrochemical Properties of Ceria-Doped SnO_2 Prepared by Sol-Gel Method

Tin dioxide (SnO2) and Ce-doped SnO2 were successfully synthesized by sol-gel method and electrochemical properties were studied in cell with Li as counter electrode. The samples were characterized by X-ray diffraction (XRD) and Transmission electron microscopy (TEM). XRD patterns presented that a second phase (CeO) was observed when the Ce content reached 5%. TEM micrograph indicated that Ce-doped SnO2 had a small particle with mean size of 30 nm. The electrochemical properties were also characterized at room temperature, and the results demonstrated that the Ce-doped SnO2 samples exhibited promising electrochemical properties and Ce doped in as-prepared samples plays an important role.

Fabrication of Ce-ReS_(2)by Molten Salt for Electrochemical Hydrogen Evolution

Renewable and economical generation of hydrogen via electrochemical methods shows great potential in addressing the energy crisis.In this study,an emerging molten salt method was adopted for the synthesis of a cerium-modifi ed rhenium disulfi de nanosheet for electrical hydrogen evolution reactions.The prepared 1%Ce-doped rhenium disulfi de(ReS_(2))sample showed promoted hydrogen evolution performance in both acid and alkaline electrolytes compared to bare ReS_(2).Generating of abundant defects in ReS_(2)exposed more reaction active sites.Moreover,adding cerium accelerated the hydrogen evolution dynamics.Hopefully,this work will off er new insight into developing ReS_(2)-based electrocatalysts for hydrogen evolution reactions.

Improvement of Coercive Force of(CoFe)_3O_4 by Doping Ce

Ce_x(CoFe)_(3-x)O_4 ferrites with different contents of Ce have been prepared by wetchemical method. The phases, morphologies and magnetic properties of the products were studied.It has been found that the products were a single phase with spinel structure and consisted of granular particles in most cases.The coercive force of the products increased with the increase of concentration of Ce￣(4+) in the reaction solution.On the other hand,if Ce￣(3+) and Ce(OH)_4 were present in the reaction solution,some rod-shape crystals in the products were observed, which causes a great increase in coercive force,and the optimum value was obtained when[Ce￣(3+)] was about 5% of the total([Ce￣(3+)]+[Ce￣(4+)]).

Low-temperature solution synthesis and characterization of Ce-doped YAG nanoparticles

Monophasic Ce3＋-doped yttrium aluminum garnet （Ce：YAG） nanoparticles with high crystallinity and tunable grain size ranging from -19-30 nm were prepared by a modified co-precipitation process with a follow-up calcination treatment. For the syn- thesis, aluminum, yttrium, and cerium nitrates were used as starting materials, ammonium sulfate as dispersant, and a combination of ammonium bicarbonate and ammonia as precipitating agent. Influence of precipitation temperature, the pH value of precipitant solu- tions, aging period, calcination conditions, and Ce-doping level were investigated for controlling the purity, particle size, and photo- luminescence performance of the Ce：YAG nanoparticles. High-purity YAG nanoparticles were prepared at pH= 10.50-11.00 and cal- cination temperatures of 850-1100 ~C with a calcination time of 3 h. With increasing Ce3＋ concentration, the peak in the emission spectra of the obtained nanopowders shifted from 529 nm for the 0.67 wt.%-Ce：YAG to 544 nm for the 3.4 wt.%-Ce：YAG, while the strongest photoluminescence intensity was observed for the 1.3 wt.%-Ce：YAG nanoparticles.

Preparation,characterization and infrared emissivity study of Ce-doped ZnO films

Ce-doped ZnO films were prepared by the sol-gel method with spin coating onto glass substrates.Zinc acetate dihydrate,ethanol,diethanolamine and cerium nitrate hexahydrate were used as starting material,solvent,stabilizer and dopant source,respectively.Structure and microstructure of the films were characterized with X-ray diffraction(XRD),field emission-scanning electron microscopy(FE-SEM) and the energy dispersive X-ray spectrometry(EDS).The infrared properties were also investigated.It was found that Ce-...

Humidity sensing properties of Ce-doped nanoporous ZnO thin film prepared by sol-gel method

The humidity sensitive characteristics of the sensor fabricated from Ce-doped nanoporous ZnO by screen-printing on the alumina substrate with Ag-Pd interdigital electrodes were investigated at different sintering temperatures.The nanoporous thin films were prepared by sol-gel technique.It was found that the impedance of the sensor sintered at 600 oC changed more than four order of magnitude in the relative humidity（RH） range of 11%-95% at 25 oC.The response and recovery time of the sensor were about 13 and 17 s,respectively.The sensor showed high humidity sensitivity,rapid response and recovery,prominent stability,good repeatability and narrow hysteresis loop.These re-sults indicated that Ce-doped nanoporous ZnO thin films can be used in fabricating high-performance humidity sensors.

Tunable luminescence from Ce-doped aluminoborosilicate glasses

A series of aluminoborosilicate glasses were prepared amounts of SiO2, A1203, H3BO3, Na2CO3, and ZrO2 with adding using the melt-quenching technique for mixture of stoichiometric of different amounts of CeO〉 The samples were investigated by means of luminescence spectroscopy. Tunable luminescence from violet to blue/green was observed from these glasses with different Xe-lamp excitation wavelengths ranging from 370 to 480 nm as well as with laser excitation of 266 and 355 nm. Moreover it was found that the possibility of tuning the light by changing of excitation wavelength was not unique. The same effect was observed by adjusting conditions for luminescence measurements as well as under exposure to β-irradiation. The obtained phenomena could be explained taking into account structural characteristics of this glass and it could be concluded that tunable luminescence results from the presence of different Ce-sites the glass matrix. Thus the results suggest that Ce-doped glasses could be considered as conversion materials for blue light-emitting diode chips to generate white light-emitting diodes.

Synthesis and photocatalytic property of Ce-doped SnO_2

Pure SnO2 and Ce-doped(1%,4%,7%,10% in mass ratio) SnO2 powders were prepared by a simple sol-gel method.The as-prepared samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),and Brunauer-Emmett-Teller(BET) specific surface area analyzers.Results showed that the 7% Ce-doped sample has a particle size of 0.1-0.3 μm with a narrow particle size distribution while the pure SnO2 was consisted of large agglomerated particles with a diameter up to several micrometers.When used as the catalyst to degrade methyl orange(MO),the 7% Ce-doped sample showed best photocatalytic property.These properties can be attributed to the large surface area and small particle size of the 7% Ce-doped sample.

Mercury removal performance over a Ce-doped V-W/TiO_(2) catalyst in an internally illuminated honeycomb photoreactor

A new type of internally illuminated honeycomb photoreactor was designed. The honeycomb catalyst prepared by using Cedoped TiO2 with 1%–2% vanadium and tungsten was employed for mercury removal from simulated industrial flue gas. The adsorption kinetics in the reaction process were studied. The results showed that the internally illuminated honeycomb photoreactor had good mercury removal performance. When the temperature was 25℃ and the ultraviolet(UV) light intensity reached 80 μW/cm2, the mercury removal efficiency reached 92.5%. The mercury removal efficiency increased significantly with the doping ratio of Ce. XPS analysis showed that the oxidation state of Ce changed from 4 to 3 in the mercury removal reaction and produced lattice oxygen, which acts as an oxidant. O2 can promote mercury removal by honeycomb catalysts;SO2 and HCl also had positive effects, while NO had an inhibitory effect on mercury removal. Kinetic research in the reaction process showed that the quasi-first-order dynamic model had good fitting results, and the correlation coefficients of the fitting results for multiple sets of experimental data were more than 0.999.