Microsphere Samples Research Articles

Preparation and surface modification of hierarchical nanosheets-based ZnO microstructures for dye-sensitized solar cells

This paper reports a simple one-step hydrothermal route for the preparation of hierarchical nanosheets-based ZnO microstructures and their application to dye-sensitized solar cells. The morphologies of the products were controlled by the dosage of the reactants. Their physical characteristics were detected by X-ray diffraction, a field-emission scanning electron microscope and a surface analyzer. It is proved that the sample of ZnO microspheres with larger surface area and stronger light-trapping capacity since the superiority of their entirely spherical structures exhibits better photoelectrochemical properties than the mixtures of ZnO microspheres and ZnO microflowers. A dye-sensitized solar cell assembled by the ZnO microspheres as photoanode shows an energy conversion efficiency of 2.94% after surface modification by tetrabutyl titanate solution at 90°C. This result is over 1.6 times higher than the non-modified cell fabricated by the ZnO microspheres on the basis of the external improvement and the stability enhancement for the dye-sensitized ZnO photoanode.

Preparation of Y3Fe5O12 Microsphere Using Bead‐Milled Nanosize Powder for Embolization Therapy Application

Y3Fe5O12 microspheres having a 20–32 μm diameter range were prepared by a spray dryer using a bead‐milled nanosize powder. The high heat generation ability in an AC magnetic field was obtained by the bead milling of a commercial powder. The yield of the 20–32 μm microspheres was 13.5% after sifting using 20 and 32 μm sieves. The heat generation ability of the microsphere sample was almost the same as that for the bead‐milled powder because the temperature enhancement mechanism was the Néel relaxation of the superparamagnetic material. Furthermore, the heat generation ability of the Y3Fe5O12 microsphere was improved by calcination at low temperature. The heat ability increased as a function proportional to the square of the increasing magnetic field for the noncalcined sample and the samples calcined at 600°C. For the samples calcined at 650°C or higher, the heat generation ability increased as a function proportional to the cube of the increasing magnetic field because of the particle growth to form single‐domain ferrimagnetic particles. The sample calcined at 650°C showed the maximum heat generation ability(W/g) of 2.4·f·H3, where f and H are the frequency (kHz) and magnetic field (kA/m), respectively.

Amine-functionalized monodispersed porous silica microspheres with enhanced CO2 adsorption performance and good cyclic stability

Carbon dioxide capture using solid adsorbent has caused more and more attention in the world. Herein, amine-functionalized monodispersed porous silica microspheres (MPSM) were prepared by the hydrolysis and condensation of tetraethoxysilane (TEOS) in a water–ethanol–dodecylamine mixed solution, then calcined at 600°C, and finally functionalized with tetraethylenepentamine (TEA). The CO2 adsorption performance of the prepared samples was measured using a Chemisorb 2720 pulse chemisorption system (Micromeritics, USA). The results showed that the specific surface area and pore volume of the 600°C-calcined SiO2 microspheres reached 921m2/g and 0.48cm3/g, respectively. All the TEA-functionalized samples exhibited good CO2 adsorption performance, which were related to the amount of loaded TEA, adsorption temperatures, and the specific surface areas of the prepared samples. An optimal TEA loading amount (34wt%) and adsorption temperature (75°C) were determined. The maximum CO2 adsorption amount (4.27mmolg−1 adsorbent) was achieved on the 600°C-calcined SiO2 microsphere sample with TEA loading of 34wt%. Repeated adsorption/desorption cycle experiments revealed that the TEA-functionalized SiO2 microspheres were good CO2 adsorbents exhibiting excellent cyclic stability.

Photocrosslinked poly(ester‐anhydride) microspheres with macroporous structure

In this work, the new method of preparation biodegradable microspheres with macroporous structure is presented. Typical methods used for generation of porous structures in microspheres obtained from preformed polymers require the use of additional substances acting as porogens. In this study, the porosity was achieved as the effect of photocrosslinking, without porogens. Microspheres were prepared using emulsion solvent evaporation technique from functional poly(ester‐anhydride)s with different amount of allyl groups in the side chains. The crosslinking was carried out by UV irradiation during the solvent evaporation (photoinitiator was introduced to polymer solution). The size of microspheres obtained was in the range of 1.7 – 4 µm (small microspheres) or 31 – 50 µm (large ones) and depended on the conditions used in emulsion formulation process. Effectiveness of the crosslinking was characterized by the content of insoluble part of samples, and it was in the range of 42–89%. The content of insoluble part of sample of microspheres and their porosity were dependent on functionality of poly(ester‐anhydride)s, the amount of photoinitiator used, and also on size of microparticles. The small particles were always more crosslinked than the large ones, but the latter were more porous than the small ones. Crosslinked microparticles indicated higher loading efficiency of model compound and appeared to degrade faster than uncrosslinked ones, probably due to their high porosity. The high porosity of microspheres obtained would enable their eventual use in pulmonary drug delivery systems or in construction of porous scaffolds for tissue engineering. Copyright © 2013 John Wiley & Sons, Ltd.

Compositional, microstructural, and vibrational characteristics of synthesized V2O5 microspheres with nanorod formation

Microspheres composed of vanadium pentoxide nanorods have been successfully synthesized using a single step solvothermal method. Field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM) analysis were used to characterize the morphology of the nanorod-like structures. The results show that the microspheres have an average diameter of 3.5μm and that the diameter of the nanorods, of which these microspheres consist, ranges from 150 to 200nm. Chemical and phase composition of the microspheres was analyzed using X-ray Photoemission Spectroscopy (XPS), X-ray diffraction (XRD), and Selective Area Electron Diffraction (SAED). XRD patterns show that the nanorods are composed of V2O5 phase. The SAED patterns confirm the polycrystalline nature of V2O5 phase in the samples. The XPS spectra indicate that the surface of the microsphere samples consist predominantly of vanadium in its V5+ oxidation state. Vibrational analysis was done using Raman spectroscopy and Fourier transform Infrared spectroscopy and the results further confirm the formation of V2O5 phase.

Nanoparticle and Microparticle Flow in Porous and Fractured Media— An Experimental Study

Summary The goal of this research was to develop methods for acquiring reservoir pressure and temperature data near the wellbore and farther out into the formation and to correlate such information to fracture connectivity and geometry. Existing reservoir-characterization tools allow pressure and temperature to be measured only at the wellbore. The development of temperature- and pressuresensitive nanosensors will enable in-situ measurements within the reservoir. This paper provides the details of the experimental work performed in the process of developing temperature nanosensors. The study investigated the parameters involved in the mobility of nanoparticles through porous and fractured media. These parameters include particle size or size distribution, shape, and surface charge or affinity to rock materials. The principal findings of this study were that spherically shaped nanoparticles of a certain size and surface charge compatible with that expected in formation rock are most likely to be transported successfully, without being trapped because of physical straining, chemical, or electrostatic effects. We found that tin-bismuth (Sn-Bi) nanoparticles of 200 nm and smaller were transported through Berea sandstone. Larger particles were trapped at the inlet of the core, indicating that there was an optimum particle size range. We also found that the entrapment of silver (Ag) nanowires was primarily because of their shape. This conclusion was supported by the recovery of the spherical Ag nanoparticles with the same surface characteristics through the same porous media used during the Ag nanowires injection. The entrapment of hematite nanorice was attributed to its affinity to the porous matrix caused by surface charge. The hematite coated with surfactant (which modified its surface charge to one compatible with flow media) flowed through the glass beads, emphasizing the importance of particle surface charge. Preliminary investigation of the flow mechanism of nanoparticles through a naturally fractured greywacke core was conducted by injecting fluorescent silica microspheres. We found that silica microspheres of different sizes (smaller than the fracture opening) could be transported through the fracture. We demonstrated the possibility of using microspheres to estimate fracture aperture by injecting a polydisperse microsphere sample. It was observed that only spheres of 20 μm and smaller were transported. This result agreed reasonably well with the measurement of hydraulic fracture aperture (27 μm), as determined by the cubic law.

SU-F-BRCD-02: Activity Assay of a Y-90 Microsphere Sample Using a Coincidence Detection System.

This work takes advantage of a newly-determined, low-uncertainty branching ratio of the internal pair production component of Y-90 decay to spectroscopically assay the activity of a Y-90 microsphere sample with a coincidence detection system (CDS). The CDS pairs a HPGe detector with a large NaI detector. The system is able to electronically filter the bremsstrahlung continuum from the photon spectrum by gating the energy signal from the HPGe with the coincidence signal. This reduces the uncertainty in the spectra measurement compared to measurements with a single HPGe detector. A series of pulsers were used to correct for counting losses. A geometric characterization was completed to find the optimal source position for measurements. An efficiency calibration of the CDS was completed using a Na-22 standard source. To validate the measurement accuracy of the CDS, the activity of a Y-90 standard activity solution from the NIST SRM program was determined and compared to the value given by NIST. The CDS was then used to determine the activity of a Y-90 microsphere sample. This value was compared to the 3.0 GBq value given by the manufacturer. The activity determined with the CDS was within 2.6% from the given activity of the NIST SRM source, which is within the expanded uncertainty associated with the CDS measurement. The activity of the Y-90 microsphere sample was determined to be 3.72 GBq +/- 1.9%. This is 19% higher than the manufacturer-stated activity of 3 GBq. This is outside the manufacturer-stated uncertainty of +/-10%. The ability of CDS to determine the activity of a Y-90 source has been validated with comparison to a NIST Y-90 standard activity solution. The use of the CDS has been extended to determine the activity of a Y-90 microsphere sample.

아민화 젤라틴 - 후코이단 미세캡슐의 제조

아민화 젤라틴 미세캡슐은 젤라틴의 양이온인 amino 그룹과 후코이단의 음이온인 sulfate 그룹과의 이온결합으로 제조되었다. 후코이단의 농도가 증가할수록 미세캡슐의 유리아미노 그룹의 함량은 감소했으며, 또한 미세캡슐로부터의 방출 속도 역시 후코이단의 농도가 증가함에 따라 감소했고 pH 1.2인 인공위액에서의 방출 속도가 pH 7.4인 PBS 에서보다 더 빠른 것을 알 수 있었다. 아민화 젤라틴 미세캡슐은 일반 젤라틴 미세캡슐보다 유리 아미노 그룹의 함량이 높아 음전하를 띄고 있는 위점막에 점착력이 커짐을 알 수 있었다. 본 연구는 아민화 젤라틴 미세캡슐을 제조하고 점착력을 살펴본 것으로서, 본 연구결과를 토대로 amoxicillin을 캡슐화한 아민화 젤라틴 미세캡슐의 헬리코박터 저해능력에 대한 연구도 진행되어야 할 것이다. Aminated gelatin microparticles were prepared with fucoidan at concentrations ranging from 0.5 to 2.0%. In order to acquire a higher primary amino group content regarding gelatin, gelatin was synthesized by using 1,2-ethylenediamine and free amino groups of aminated gelatin microsphere sample uncrosslinked or crosslinked with fucoidan have been determined by using trinitrobenzensulfonic acid (TNBS) methods. At the smallest fucoidan concentration, the free amino group content of the aminated gelatin microparticles was highest and decreased when fucoidan concentrations were increased. Furthermore, as concentration of fucoidan increased, the release from microparticles decreased. The <TEX>$in$</TEX> <TEX>$vitro$</TEX> gastric mucoadhesion of microparticles were evaluated by using fluorescent-labeled microparticles in an isolated and perfused mouse stomach. The gastric mucoadhesion of the aminated gelatin microparticles was significantly improved compared with that of gelatin microparticles.

Young’s modulus of PS/CeO2 composite with core/shell structure microspheres measured using atomic force microscopy

Organic–inorganic composite microspheres with PS as a core and CeO2 as a shell were synthesized by in situ chemical precipitation method. The size of PS core was 117, 163, 206, and 241 nm, respectively, and the shell thickness was about 10 nm. The CeO2 shell was composed of a large number of nanoparticles, of which the size was 4–6 nm. Atomic force microscopy was employed to probe the mechanical properties of core–shell structured ceria-coated polystyrene (PS/CeO2) composite microspheres. On the basis of Hertz’s theory of contact mechanics, compressive moduli were measured by the analysis of force–displacement curves captured on the microsphere samples. For a fixed CeO2 shell thickness, the Young’s modulus of composite microspheres increased with an increase of PS core size. The calculated Young’s moduli (E) values of composites for 136, 185, 242, and 261 nm in diameter were 5.78 ± 0.9, 7.23 ± 1.3, 11.46 ± 1.7, and 14.54 ± 1.4 GPa, respectively. The results revealed the effect of the CeO2 shell on the elastic deformation of the PS core. This approach will provide fundamental insights into the actual role of organic/inorganic core/shell composite abrasives in chemical mechanical polishing.

Infrared Attenuated Total Reflection Spectroscopy of Quartz and Silica Micro- and Nanoparticulate Films

Studies on particulate quartz and silica films were performed using Fourier transform infrared spectroscopy (FT-IR) via attenuated total reflection (ATR). Based on the fact that measurements in the visible and near-infrared (vis/NIR) spectral range are already applied to spectrally distinguish disturbed from undisturbed soils, measurements in the mid-infrared (MIR) regime were performed to further investigate the utility of longer wavelengths toward this analytical problem. Natural particulate quartz samples were selected to provide a simplified surrogate for the dominating component of most soil matrices; water was added to simulate weathering processes of this matrix. Adding water to the pristine quartz particulate film resulted in a strong spectral shift of the asymmetric Si–O–Si stretch vibration at 1090 cm–1, thus substantiating the hypothesis of a size-related shift of the absorption wavelength due to changes in the particle size distribution within the evanescent field that is extending a few micrometers into the particle layer near the ATR surface. Monodisperse soda lime glass spheres and silica microsphere samples were then investigated at simulated weathering conditions to corroborate this assumption. The obtained results indeed demonstrate that spectra recorded at monodisperse particles do not reveal any spectral shifts during simulated weathering, which again confirms a particle size-related effect. In addition, studies using unpolarized and polarized IR radiation revealed a distinct correlation between the shifts of the major absorption features, i.e., the TO modes, and the particle size.

Measuring and interpreting point spread functions to determine confocal microscope resolution and ensure quality control

This protocol outlines a procedure for collecting and analyzing point spread functions (PSFs). It describes how to prepare fluorescent microsphere samples, set up a confocal microscope to properly collect 3D confocal image data of the microspheres and perform PSF measurements. The analysis of the PSF is used to determine the resolution of the microscope and to identify any problems with the quality of the microscope's images. The PSF geometry is used as an indicator to identify problems with the objective lens, confocal laser scanning components and other relay optics. Identification of possible causes of PSF abnormalities and solutions to improve microscope performance are provided. The microsphere sample preparation requires 2-3 h plus an overnight drying period. The microscope setup requires 2 h (1 h for laser warm up), whereas collecting and analyzing the PSF images require an additional 2-3 h.

The imprinting induce‐fit model of specific rebinding of macromolecularly imprinted polymer microspheres

AbstractThe rebinding behavior of protein‐imprinted hydrogel is different from classical small molecularly imprinted polymer especially in protein aggregating state and interaction changeability between protein and imprinted sites. BSA‐imprinted calcium alginate‐hydroxy ethyl cellulose microspheres were prepared, and the rebinding behavior was studied. An “imprinting induce‐fit model” was proposed to describe the rebinding property of protein‐imprinted hydrogel. Three kinds of different interacting forms between protein and imprinted hydrogel were discovered by Scatchard analysis. Slogistic fit analysis of rebinding rate coefficient was carried out, and the imprinted hydrogel was found capable of promoting rebinding through induce‐fit behavior. Higher imprinting efficiency was found in microsphere samples with lower crosslinking density. Rebinding regression equation was established, and the rebinding quantity was computable with parameters including BSA aggregate concentration [Pn], dissociating rate (k1), and single molecule rebinding rate (k2). The experimental and calculated rebinding concentration were compared, and errors between −9.43% and 5.59% were found. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122:1847–1856, 2011

Polishing behavior of PS/CeO 2 hybrid microspheres with controlled shell thickness on silicon dioxide CMP

Organic–inorganic composite microspheres with PS as a core and CeO 2 nanoparticles as a shell were synthesized by in situ decomposition reaction of Ce(NO 3) 3 on the surfaces of PS microspheres prepared through soap-free emulsion polymerization. The shell thickness of the composite microspheres could be turned by varying the concentration of Ce(NO 3) 3 in the reaction solution. The whole process required neither surface treatment for PS microspheres nor additional surfactant or stabilizer. The as-synthesized PS/CeO 2 composite microsphere samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Oxide chemical mechanical polishing (CMP) performance of the PS/CeO 2 composite abrasives with different shell thickness was characterized by atomic force microscopy (AFM). The results indicated that the as-prepared core–shell structured composite microspheres (220–260 nm in diameter) possessed thin shell (10–30 nm) composed of CeO 2 nanoparticles (particle diameter of 5–10 nm), and the final CeO 2 contents of the composite microspheres ranged from 10 to 50 wt%. A possible mechanism for the formation of PS/CeO 2 composite microspheres was discussed also. The CMP test results confirmed that the novel core–shell structured composite abrasives are useful to improve oxide CMP performance. In addition, there is an obvious effect of shell thickness of the composite abrasives on oxide CMP performance.

Hydrophilically Coated Gigaporous Polystyrene Microspheres and their Application in High-Speed Protein Chromatography

Gigaporous poly (styrene-divinylbenzene) (PS) microspheres have been effectively hydrophilized by coating with hydrophobically modified agarose (phenoxyl agarose, Agap). The effect of the phenoxy content on the amount of Agap adsorbed onto the PS surface was examined and various samples of microspheres, differing in surface Agap density, were prepared. After coating, the hydrophilicity of gigaporous PS microspheres was found to be greatly enhanced and the gigaporous character of PS microspheres was well maintained. The modified particles were further coupled with DEAE groups to prepare a DEAE anion exchange medium (DEAE-AP). A column packed with DEAE-AP showed low back pressure and high protein resolution at high flow velocity. Notably, the DEAE-AP column could completely separate a model protein mixture at a flow velocity of 3612 cm/h within 2 min. The results indicate that the gigaporous matrix has considerable advantages for high-speed protein chromatography.

Self-Assembled Mesoporous Hierarchical-like In2S3Hollow Microspheres Composed of Nanofibers and Nanosheets and Their Photocatalytic Activity

Novel template-free hierarchical-like In(2)S(3) hollow microspheres were synthesized using thiosemicarbazide (NH(2)NHCSNH(2)) as both a sulfur source and a capping ligand in a ethanol/water system. In this study, we demonstrate that several process parameters, such as the reaction time and precursor ratio, strongly influence the morphology of the final product. The In(NO(3))(3)/thiosemicarbazide ratios were found to effectively play crucial roles in the morphologies of the hierarchical-like In(2)S(3) hollow microsphere nanostructure. With the ratios increasing from two to four, the In(2)S(3) crystals exhibited almost spherical morphologies. The synthesized products have been characterized by a variety of methods, including X-ray powder diffraction (XRD), Raman spectroscopy, field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray (EDX) analysis, X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffused reflectance spectroscopy (UV-vis DRS). XRD analysis confirmed the tetragonal structure of the In(2)S(3) hollow microspheres. The products show complex hierarchical structures assembled from nanoscale building blocks. The morphology evolution can be realized on both outside (surface) and inside (hollow cavity) the microsphere. The surface area analysis showed that the porous In(2)S(3) possesses a specific surface area of 108 m(2)/g and uniform distribution of pore sizes corresponding to the size of pores resulting from the self-assembled structures with flakes. The optical properties of In(2)S(3) were also investigated by UV-vis DRS, which indicated that our In(2)S(3) microsphere samples possess a band gap of ∼1.96 eV. Furthermore, the photocatalytic activity studies revealed that the synthesized In(2)S(3) hollow microspheres exhibit an excellent photocatalytic performance in rapidly degrading aqueous methylene blue dye solution under visible light irradiation. These results suggest that In(2)S(3) hollow microspheres will be an interesting candidate for photocatalytic detoxification studies under visible light radiation.

An HC-PCF Fluorescence Spectrocopy for Detection of Microsphere Samples Based on Refractive Index Scaling Law

This paper illustrates an efficient fluorescence detection of micro particles using hollow-core photonic crystal fibers (HC-PCFs) by applying the refractive index (RI) scaling law. The variations in the central wavelength for different filling material indices are illustrated for most commonly available HC-PCFs that have cladding made of pure fused silica with array of air holes running along the entire length of the fiber. The proposed concept is verified by immobilizing fluorescent microsphere samples inside two HC-PCFs of different central wavelengths and the quantification of fluorescence inside the fibers is performed through spectroscopic analysis. The sensitivity has been compared for similar fiber with different dispersed media and different fibers with same dispersed medium.

Comparison of broadband and ultrabroadband pulses at MHz and GHz pulse‐repetition rates for nonlinear femtosecond‐laser scanning microscopy

Nonlinear optical imaging of human skin and of polychromatic microspheres was carried out to compare and evaluate the imaging properties of three different excitation femtosecond lasers: a spectrally tunable 80 MHz Ti: sapphire oscillator that produced 100 fs pulses (spectral width ∼10 nm) and two ultrabroadband Ti: sapphire oscillators with repetition rates of 85 MHz and 1 GHz. The latter of these two and the 100 fs laser were combined with a laser scanning microscope (TauMap). The intensities of images of the polychromatic microsphere samples obtained with both lasers are in accordance with the usual dependence of two-photon processes on laser pulse parameters, i.e. the intensity is proportional to the square of the mean laser power and the reciprocal pulse duration. In contrast to that, skin images measured with all three different excitation sources with mean powers of each laser adjusted to the particular pulse length and repetition rate exhibited discrepancies from this relation. For characterization of the ultrabroadband GHz laser, the measurements are supplemented by spectra of second-harmonic-generation signals of urea and collagen.

Preparation and size determination of monodisperse silica microspheres for particle size certified reference materials

Five samples of monodisperse SiO2 microspheres used for certified reference materials for particle size were synthesized by the seed-growth method, that is, through hydrolysis and condensation of tetroethylorthosilicate in a mixture of ethanol and water, using amoniua as catalyst. Their nominal diameters were 0.15μm, 0.3μm, 0.5μm, 1μm, and 2μm. The average diameters of these microspheres were accurately determinated by SEM array-sizing method, and the microspheres with 1μm and 2μm nominal diameters were determined by both SEM array-sizing method and optical array-sizing method, while the particle size distribution of these spheres was determined by SEM. The measurement errors for each sample were quantitatively assessed. The SEM magnification was calibrated with a SEM calibration standard traceable to CNIM (China National Institute of metrology), while the optical microscopy magnification was calibrated with a NIST stage micrometer (SRM 2800). The average diameters determined by SEM and optical microscopy were identical to each other. For comparison, the average diameter of these microspheres was also measured by other independent techniques -light scattering and photo-correlation methods, and the obtained data agreed well with that obtained by the array sizing method.

Preparation, characterization and oxide CMP performance of composite polystyrene-core ceria-shell abrasives

To improve their chemical mechanical polishing (CMP) performance, composite polystyrene-core ceria-shell (PS/CeO 2) abrasives were synthesized by in-situ chemical precipitation. The as-synthesized PS/CeO 2 composite microspheres samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) and zeta potential analysis. Oxide CMP performance of the PS/CeO 2 composite abrasives was investigated by atomic force microscopy (AFM). The results indicate that PS/CeO 2 composite abrasives with a core–shell structure are obtained successfully. The particle size of as-prepared PS/CeO 2 composite particles is about 140 nm, and the PS microspheres are uniformly coated by CeO 2 nanoparticles. The surface of thermal oxide film polished by PS/CeO 2 composite abrasives has lower topographical variations and surface roughness than that polished by CeO 2 nanoparticles. After polished by composite abrasives, root-mean-square roughness of wafer within 5 μm × 5 μm area is 0.331 nm, and material removal rate can reach 484.5 nm/min.

Preparation and characterization of monodisperse Ce-doped TiO 2 microspheres with visible light photocatalytic activity

Monodisperse Ce-doped TiO 2 microspheres with visible light photocatalytic activity were prepared by a facile solvothermal process using urea as a hydrolysis inhibitor, and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance spectrum (UV–vis DRS). The photocatalytic activity of the resulting Ce-doped TiO 2 microspheres was evaluated by photodegradation of methylene blue under visible light irradiation. The results showed that the doping content of Ce and amount of urea used in the starting reaction medium could affect the surface texture and dimension of Ce-doped TiO 2 microsphere, respectively. All the Ce-doped TiO 2 microsphere samples showed higher photocatalytic activity than undoped TiO 2. Sample containing 1 at% Ce exhibited the highest photocatalytic activity among the Ce-doped TiO 2 microsphere samples. With ease of recovery from treated water as well as fine durability, the as-synthesized Ce-doped TiO 2 microspheres might hold potential for application in wastewater treatment.