Improved luminescence and photocatalytic properties of Sm3+-doped ZnO nanoparticles via modified sol-gel route:A unified experimental and DFT+U approach

In the current study,a modified sol-gel route was used to produce undoped and Sm³⁺ doped(1 mol%,3 mol% and 5 mol%) ZnO nanoparticles(NPs).The study of opto-structural properties of Sm³⁺ doped NPs was carried out both experimentally and theoretically.Complete dissolution of Sm³⁺ ions into the ZnO lattice is obviously seen from X-ray diffraction(XRD) analysis.Morphological evolution with doping was studied using field emission scanning electron microscopy(FESEM) an...     

Aluminium and cerium co-doped ZnO nanoparticles:Facile and inexpensive synthesis and visible light photocatalytic performances

Facile combustion route synthesized Al and Ce co-doped ZnO nanoparticles photocatalysts were characterized using XRD,SEM,BET,EDS,UV-visible DRS,PL,photocurrent and EIS techniques.XRD and SEM analyses identify that crystallite and particle size is reduced from 13.26 to 11.88 nm with introduction of Al and Ce into ZnO which assists inhibiting the recombination of photo generated charge carriers.UVvisible DRS spectra indicate that optical assimilation of ZnO is significantly increased to visible region(-406 nm)and band gap reduces from 3.18 to 3.06 eV with introduction of Al and Ce co-dopants.Electrochemical impedance spectroscopy analysis under visible light illumination confirms the enhancement in visible light activity of Al and Ce co-doped ZnO nanoparticles as photocatalysts.The enhanced activity of Al and Ce co-doped ZnO photocatalyst can be ascribed to enhanced light assimilation,high surface area and efficient charge transfer process.Our results reveal that by incorporating precise amount of Al(~2%)and Ce(~2%)into ZnO,a highly efficient catalyst can be synthesized that have degraded almost 95%methyl orange(MO)dye in just 45 min.Further,the influence of various operational parameters such as solution pH,catalyst dose,dye concentration,airflow rate and light intensity on photodecomposition of MO was evaluated.Furthe rmore,a possible mechanism for Al and Ce modified ZnO was proposed and designed photocatalysts demonstrates good stability in aqueous medium.     

Enhanced visible light photoactivity of TiO2/SnO2 films by tridoping with Y/F/Ag ions

The Y, F, and Ag tridoped TiO₂/SnO₂ composite nanocrystalline film (YFAg–TS) with prominent photocatalytic performance was prepared by the modified sol–gel method and was characterized by utilizing X-ray diffraction (XRD), differential thermal and thermogravimetric (DTA–TG) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) method, ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS), and photoluminescence (PL). The XRD and DTA–TG results expose that the YFAg–TS catalyst is a mixed phase consisting of anatase, rutile, and chlorargyrite, which is beneficial to improving the photocatalytic performance of TiO₂. The SEM, TEM, and BET results disclose that the YFAg–TS film has smaller nanoparticles, higher specific surface area, and narrower pore size compared with pure TiO₂ film. The XRD and TEM results exhibit that a part of yttrium can enter the TiO₂ lattice to induce lattice distortion. The XPS results confirm the presence of Y³⁺ state in the YFAg–TS sample, and Y³⁺ ions can act as the trapping site of electrons to expedite the separation of electrons and holes. The UV–vis DRS results reveal that the YFAg–TS film has an obvious absorption edge shift and a narrower bandgap (2.70 eV) compared with pure TiO₂ film. The PL results show that the YFAg–TS film has the highest photogenerated electrons and holes separation efficiency and charges transfer efficiency among all samples. The photocatalytic activity of the YFAg–TS was assessed by monitoring the degradation of methyl green and formaldehyde solution. The results manifest that the YFAg–TS film has high stability and excellent photocatalytic performance. The possible synergistic photocatalytic mechanism of YFAg–TS films has been discussed in this paper.     

Nd-doped ZnO as a multifunctional nanomaterial

Chemically synthesised ZnO and Nd-doped ZnO nanoparticles were investigated for structural, optical, magnetic properties along with photocatalytic activity. Transmission electron microscopy measurement was performed on the undoped and doped ZnO nanoparticles. Compared to the undoped ZnO, Nd-doped ZnO nanoparticles showed enhanced photoluminescent and ferromagnetic properties. The Nd-doped ZnO nanoparticles also showed improved photocatalytic properties compared with the undoped ZnO nanoparticles. Furthermore, the effect of UV light irradiation was studied with thermoluminescence (TL) and photoluminescence (PL) measurement techniques. It was found that in case of Nd-doped ZnO nanoparticles TL intensity increased while the green emission in PL spectra decreased with UV-light irradiation. This was attributed to the production of more surface defects on UV irradiation on Nd-doping.     

Influence of manganese rate on structural,optical and electrochemical properties of CeO2 thin films deposited by spray pyrolysis: Supercapacitor applications

The present work aimed to investigate the electrochemical properties of ITO substrates in propylene carbonate (PC) with 0.5 mol/L lithium perchlorate (LiClO₄) medium in the presence of elaborated thin films of cerium dioxide pure and doped with manganese at varying percentages. Ce_1–xMn_xO₂ (x = 0 wt%, 2 wt%, 4 wt% and 6 wt%) were successfully deposited by the spray pyrolysis (SP) technique on the glass substrate and ITO at 450 °C. The effects of manganese (Mn) doped thin films Ce_1–xMn_xO₂ were studied and investigated by using different analyses namely X-ray diffraction (XRD) analysis, Raman spectroscopy method, UV–Vis spectrophotometer technique, atomic force microscopy (AFM) analysis and electrochemical properties. XRD data obtained present a polycrystalline with a face-centred cubic structure of fluorite type. Raman results of undoped and Mn doped thin films show two peaks at 465 and 600 cm^?1, due to the formation of extrinsic oxygen vacancies by the incorporation of Mn into Ce_1–xMn_xO₂ matrix. Energy dispersive spectroscopy (EDS) data show the presence of Ce, O, and Mn elements in the elaborated films. The AFM results reveal that the surface roughness decreases with increasing Mn rate. Further, band gap energy of thin films decreases with increasing in Mn rate due to the formation of defect state between valence and conduction band. The storage capacity of the elaborated Ce_1–xMn_xO₂/ITO/PC + LiClO₄ electrode reaches a maximum of 1.997 mF in the presence of 6 wt% of Mn.     

Preparation and application of ZnO doped Pt-CeO2 nanofibers as electrocatalyst for methanol electro-oxidation

ZnO doped Pt/CeO₂ nanocomposites were prepared by electrospinning and reduction impregnation. X-ray diffraction (XRD), transmission electron microscopy (TEM), energy disperse spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the nanocomposites. It is observed that ZnO and CeO₂ form the hexagonal wurtzite phase and cubic fluorite phase in the nanocomposite, respectively, whilst Pt nanoparticles (NPs) with the number-averaged size of ca. 3.1 nm are uniformly distributed on the surface of nanofibers. The mass fraction of Pt NPs in the nanocomposites is about 10 wt%. The doping of ZnO is effective to promote reactive oxygen species, surface reaction sites and the interaction between Pt and oxides. The catalytic performance of nanocomposites was evaluated by the methanol electro-oxidation, indexed with the catalytic activity, stability of catalyst. As a result, it is found that the nanocomposite exhibits much higher activity and stability for methanol oxidation than the undoped Pt/CeO₂ catalyst.     

Synthesis,Characterization and Photocatalytic Studies of La,Dy-doped ZnO nanoparticles

Rare earth La Dy co-doped ZnO nanoparticles (Zn_0.98La_0.01Dy_0.01O, Zn_0.96La_0.02Dy_0.02O, Zn_0.94La_0.03Dy_0.03O, and Zn_0.92La_0.04Dy_0.04O) were synthesized by co-precipitation method at temperature of 500 °C for 2 h in air. The synthesized samples were characterized by powder X-ray diffraction (XRD), FE-SEM/EDS and UV–Visible spectrophotometer. The prepared nanoparticles exhibit a hexagonal wurtzite structure as observed from XRD measurements. It was observed that the La Dy co- doped ZnO nanoparticles (Zn_0.98La_0.01Dy_0.01O, Zn_0.96La_0.02Dy_0.02O, Zn_0.94La_0.03Dy_0.03O, and Zn_0.92La_0.04Dy_0.04O) exhibit higher optical absorbance spectrum at 400 nm to 800 nm wavelength due to its smaller crystal size (12.2 nm) as compared to the un- doped ZnO nanoparticles (253.1 nm). The photocatalytic activity of rare earth La Dy co- doped ZnO nanoparticles were studied by performing the decomposition of methylene blue dye solution under UV light irradiation within 0–4 h. The methylene blue dye solution was considerably photodegraded by Zn_0.92La_0.04Dy_0.04O photocatalyst under UV light irradiation within 2–4 h to the efficiency of 96 %. The pseudo first order rate constant of the degradation was found to be 0.0264 S^?1. The degradation mechanisms are discussed in this work.     

Tm-doped ZnO nanorods as a TCO for PV applications

In photovoltaic(PV) devices, a transparent conducting oxide(TCO) film is used as a transparent electrode which permits sun rays to reach to the photoactive semiconducting layers and also to collect the photogenerated electrons. Due to their electrical and optical properties zinc oxide(ZnO) based thin films and nanostructures are considered as an abundant and safer option for TCOs. In this study, undoped and thulium(Tm)-doped ZnO nanorods(NRs) were produced on glass substrates via spin coating and hydrothermal methods. The ZnO samples were described by X-ray diffractometry(XRD). Morphological features of the ZnO samples were investigated with scanning electron microscopy(SEM). It is observed that the all ZnO samples have nanorod shape. The average rods diameter is between 75 and 100 nm. Also,the rods length is found to be between 0.96 and 1.62 μm. Electrical properties of the ZnO samples were performed via four probe method. The conductivity increases with measurement temperature and Tm doping. Optical spectra of the ZnO samples were measured in UV-Vis range and the band gap(E_g) is found to be 3.35 eV.     

Synthesis and characterization of Co_(1-2x)Ni_xMn_xCe_yFe_(2-y)O_4 nanoparticles

Spinel ferrite Co_(1-2 x)Ni_xMn_xFe_(2-y)Ce_yO_4(0.0≤x=y≤0.3) nanoparticles(NPs) were prepared by sol-gel auto-combustion method.The synthesized NPs were examined using several techniques such as X-ray diffraction(XRD),field emission scanning electron microscopy(FE-SEM) coupled with EDX and elemental mapping,transmission electron microscopy(TEM),Fourier-transform infrared spectroscopy(FT-IR),and a vibrating sample magnetometer(VSM).The analysis of the crystal structure and the phase identification of samples indicates the formation of spinel cubic phase with the occurrence of CeO_2 as secondary phase when the content of Ce substitution element increases.In addition,all produced samples exhibit cubic symmetry with space group Fd3m.TEM confirms the presence of two phases,i.e.,the cubic spinel ferrite and the cubic cerium oxide(CeO_2).The characteristics of hysteresis loops reveal the soft ferrimagnetic nature of the different synthesized samples.The saturation(M_s) and remanent(M_r) magnetizations fall on increasing the content of substituting elements.Compared with pure CoFe_2O_4 NPs,the value of coercive field(H_c) slightly increases for x=y=0.1 and x=y=0,2 NPs.Then,H_c reduces with further increasing the x and y contents.The squareness ratio is found to be in the 0.528-0.400 interval,indicating the single domain NPs with uniaxial anisotropy for the different produced NPs.The magneto crystalline anisotropy constant(K_(eff)),anisotropy field(H_a),magneton number(n_B) and the demagnetizing field(N) were also determined and discussed.     

Physicochemical properties of Li3Ba2La3(MoO4)8:Eu,Tb red-emitting phosphor for solid state white lamps

In this work,combustion synthesis was used for the first time to fabricate a phosphor material with red emission for applications in solid-state white-light lamps.We synthesized a material with emission wavelength at λ_em=617 nm,excited under long UV-blue wavelength based on Eu³⁺,Tb³⁺-activated molybdates Li₃Ba₂(La_1-x-yEu_xTb_y)₃(MoO₄)₈ with 0 ≤ x ≤1 and 0 ≤ y ≤ 1.A series of pow...     

Synthesis and characterization of yttrium and antimony codoped SnO₂ conductive nanoparticles

Y was used as a dopant in preparing conductive powder to improve its performance. Y and Sb co-doped SnO2 conductive nanoparticles were prepared by the complexation-coprecipitation method with Sn,Sb2O3 and Y2O3 as the raw materials. Crystal phase,thermal behavior and structure of the prepared conductive nanoparticles were characterized by X-ray diffraction(XRD) ,thermal analysis(TG-DSC) ,Fourier transform infrared(FTIR) and transmission electron microscopy(TEM) techniques,respectively. The Y and Sb co-doped SnO2 conductive nanoparticles with a structure of tetragonal rutile had intense absorption in 4000-2500 cm-1,and the diameter ranged from 10 to 30 nm. The resistivity of Y and Sb co-doped SnO2 conductive nanoparticles was as low as 0.09 Ω·cm which was 4.6 times lower than that of Sb doped SnO2 conductive nanoparticles.     

CO oxidation and 4-nitrophenol reduction over ceria-promoted platinum nanoparticles impregnated with ZSM-5 zeolite

Active new ceria-promoted platinum supported on ZSM-5 catalysts were prepared and characterized by X-ray diffraction(XRD),Fourier transform infrared spectra(FTIR),transform electron microscopy(TEM),temperature programmed desorption(TPD),and FTIR of CO adsorption.The samples were prepared by the incipient wetness impregnation method and calcined at 500℃.The XRD patterns and FTIR spectra prove that the zeolite framework is kept unaltered after metal loadings.TEM images prove the presence of Pt nan...     

Design and synthesis of Fe-Ce-O@C with efficient photocatalytic activity

Fe-Ce-OH@AR14 was obtained via the adsorption of acid red 14(AR14) on Fe-Ce-OH prepared by the codeposition of cerium nitrate hexahydrate,ferric nitrate nonahydrate,and ammonia,and then Fe-Ce-O@C with high photocatalyic efficiency was synthesized by the calcination of Fe-Ce-OH@AR14 in N₂.For comparison,Fe-Ce-O was also prepared by the calcination of Fe-Ce-OH in N₂.The obtained materials were characte rized by X-ray diffraction(XRD),Raman,X-ray photoelectron spectroscopy(XPS...     

Preparation of Nano-TiO2 Doped with Cerium and Its Photocatalytic Activity

Cerium-doped titanium dioxide nano-powders were prepared through the sol-gel method and the compound sampies were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, and UV/Vis diffuse reflectance spectra （DRS）. The photocatalytic activity was evaluated by photocatalytic degradation of phenol in water. The results of XRD, TEM, and DRS show that pure TiO2 and Ce-doped TiO2 powder crystallines are a mixture of anatase and rutile ; the doping can retard the development of the grain size of TiO2 and decrease the diameter of TiO2 from more than 20 nm of pure TiO2 to about 10 nm; the doped TiO2 can improve the light absorption of TiO2 and suitable doping content tends to move the DRS spectrum of TiO2 towards visible light, but too much doping is not good for the light absorption ability. The results of the photocatalytic experiments show that doping with Ce content of 0.08% -0.4% can increase the photocatalytic activity of TiO2; however, doping with Ce content of 0.5% -2.5% can significantly decrease the photocatalytic activity of TiO2. The favorite doping content is 0.4% in the range of our experiments.     

Synthesis and characterization of yttrium and antimony codoped SnO2 conductive nanoparticles

Y was used as a dopant in preparing conductive powder to improve its performance. Y and Sb co-doped SnO₂ conductive nanoparticles were prepared by the complexation-coprecipitation method with Sn, Sb₂O₃ and Y₂O₃ as the raw materials. Crystal phase, thermal behavior and structure of the prepared conductive nanoparticles were characterized by X-ray diffraction (XRD), thermal analysis (TG-DSC), Fourier transform infrared (FTIR) and transmission electron microscopy (TEM) techniques, respectively. The Y and Sb co-doped SnO₂ conductive nanoparticles with a structure of tetragonal rutile had intense absorption in 4000-2500 cm^?1, and the diameter ranged from 10 to 30 nm. The resistivity of Y and Sb co-doped SnO₂ conductive nanoparticles was as low as 0.09 Ω·cm which was 4.6 times lower than that of Sb doped SnO₂ conductive nanoparticles.     

Synthesis and characterization of rare earth metal doped tungsten trioxide photocatalyst for degradation of Rhodamine B dye

Nowadays,it is concern for researchers that due to high recombination rate of photogenerated charge carriers in tungsten trioxide(WO₃) nanoparticles,the future applications are limited in the field of photocatalysis.Herein we attempt to synthesize tungsten trioxide nanoparticles with different doping concentrations of lanthanum i.e.2 wt%,4 wt%,6 wt% and 8 wt%.The synthesized samples were characterized by using various characterization techniques:X-ray diffraction(XRD),Raman spectrosco...     

Nucleation and epitaxy growth of high-entropy REBa2Cu3O7-δ(RE=Y,Dy,Gd,Sm,Eu)thin films by metal organic deposition

High-entropy REBa₂Cu₃O_7-δ(RE=Y_0.7+Dy_0.2+Gd_0.2+Sm_0.2+Eu_0.2)(HE-REBCO) superconducting films doped with multiple rare earth elements were successfully fabricated with thickness up to 800 nm by a trifluoroacetate-metal organic deposition(TFA-MOD).The enhanced entropy change ΔS of the HEREBCO system promotes the c-axis growth of REBCO thin film in the competition with a/b-axis growth.The microstructure and elemen...     

Exploring the energy transfer processes in Lu2(1–x)Y2xSiO5:Ce crystals

A systematical exploration of energy transfer processes in Lu_(2(1-x)Y_2 xSiO_5:Ce(LYSO) crystals under vacuum ultraviolet-ultraviolet(VUV-UV) excitation was implemented. The relationship between energy transfer and scintillation properties was established. It is revealed that there are mainly three energy transfer types in the crystal i.e. host → Ce1/Ce2/STEs, Ce1 →Ce2 and STEs → Ce1/Ce2. The influence of Y content of the LYSO crystals on the energy transfer efficiency of the above processes was carefully analyzed. Besides, we find a special component of the crystal i.e. Y content = 45 at% at which the energy resolution and light output of the crystal perform the worst.     

Preparation of epoxy resin/rare earth doped aluminate nanocomposite toward photoluminescent and superhydrophobic transparent woods

A translucent wooden substrate with long-lasting phosphorescence,high photostability and durability,tough surface,ultraviolet protection,high optical transmittance,and superhydrophobicity was developed.This long-lasting phosphorescent wooden substrate is able to continue emitting light for extended time periods.Lignin-modified wood(LMW) was immobilized with a solution of epoxy resin(ER) and rare-earth doped aluminate(REDA) phosphor nanoparticles(NPs).For an improved dispersion of pigment,REDA wa...     

Structure and magnetostriction of high Pr/Ce-content (Tb0.2Pr0.8)1–xCexFe1.93 Laves compounds

The light rare earth Pr/Ce-contained (Tb_0.2Pr_0.8)_1–xCe_xFe_1.93 (0 ≤ x ≤ 1.0) intermetallics were arc melted and magnetoelastic properties were investigated. The compounds of x ≥ 0.40 are found to stabilize at ambient pressure in a single Laves phase with MgCu₂-type C15 structure, which is attributed to the strong Ce 4f bonding. The mixed-valence behavior, with a support of the deviation from the linear Vegard’s law for both lattice parameter a and saturation magnetization M_S, is observed at room temperature. The easy magnetization direction (EMD) was determined by the analysis of XRD on both magnetically aligned samples and the (440) splitting, that is, EMD lies toward <111> axis for x ≤ 0.50 rotating to <110> for x = 0.60, accompanied with the structural distortion from rhombohedral to orthorhombic. The substitution of Ce for Tb/Pr is conductive to the reduction of magnetocrystalline anisotropy, giving rise to an improvement of the low-field magnetostriction. The excellent magnetoelastic properties can be tailored by the Ce introduction, e.g., the spontaneous magnetostriction coefficient λ₁₁₁ as large as 1150 × 10^?6 for x = 0.40, and the low-field induced magnetostriction achieving a high value of λ_a = 180 × 10^?6 at 80 kA/m for x = 0.60. The excellent magnetoelastic properties and the combination in high Pr-content with low cost, suggest promising prospects in applications.