Enhanced visible light photocatalytic performance of Sb-doped (BiO)2CO3 nanoplates

Sb-doped (BiO)₂CO₃ nanoplates have been successfully fabricated via a facile hydrothermal method. XRD patterns, XPS spectra, SEM and TEM images demonstrated that doping with antimony (Sb) has no effect on the crystal phase, morphology and structure of (BiO)₂CO₃ nanoplates. However, the red shift of diffraction peak in the 2θ range of 29–32° was observed, which could be attributed to the substitution of larger radius of Bi atoms by lower radius of Sb atoms resulting in the decrease of lattice parameters. The photocatalytic performance of Sb-doped (BiO)₂CO₃ nanoplates was evaluated by the degradation of RhB upon visible light irradiation. It was found that the visible-light-induced photocatalytic activity of Sb-doped (BiO)₂CO₃ nanoplates was significantly improved, which was mainly attributed to its enhanced surface area and electron transfer rate. It was proposed that RhB photodegradation proceeded through a photosensitization pathway upon visible light irradiation.     

Superfine and closely-packed TiO2/Bi2O3 lamination on graphene nanoplates with high photocatalytic activity

Graphene/TiO₂–Bi₂O₃ nanohybrids were synthesized by one-step PAA-assisted hydrothermal method with a low-temperature treatment. Their morphology, structure and photocatalytic property were investigated accordingly. The SEM and TEM results showed that the nanohybrids composed of TiO₂ and Bi₂O₃ nanoparticles with the size of about 10 nm were uniformly covered on the graphene sheets. Furthermore, the resultant samples presented excellent photocatalytic activity for RhB and recycle property, in which 95% RhB was degraded within 10 min and a good activity was maintained in the seven recycling tests, besides the hybrids also possess good activity in visible light. The enhancement of photocatalytic activity is attributed to efficient transfer of the photogenerated electrons from the CB of semiconductor nanoparticles to graphene and the homogeneity of nanoparticles.     

Perforative pore formation on nanoplates for 2D porous MXene membranes via H2O2 mild etching

MXene (Ti₃C₂T_x) is a novel, two-dimensional (2D) layered material that is atomically thin, exhibits good mechanical strength, and is ideal for fabricating efficient membranes for molecular separation. However, the applications of MXene membranes are limited by their low water permeability owing to narrow channels and high tortuosity. A novel strategy for introducing artificial pores on the surface of MXene nanosheets via gentle in situ chemical etching with hydrogen peroxide (H₂O₂) to prepare porous MXene nanosheets (PMS) is reported herein. This greatly increases the water permeability of MXene membranes while retaining the high rejection of small-molecule dyes. Permeable pores generated on MXene nanosheets transform the transport model of water molecules in the membrane from typical horizontal transport pathways dominated by interlayer channels to longitudinal–lateral three-dimensional transport pathways, affording increased water molecule transport channels and reduced transport distance. Based on different etching conditions, the obtained membranes exhibit high pure-water permeability ranging from 9.37 to 42.48 L m⁻² h⁻¹ bar⁻¹. Moreover, mild etching maintains the 2D structure of the membrane and retains a nearly complete rejection of congo red dye. This study provides a novel and effective strategy for preparing high-performance porous laminar MXene membranes for dye-separation applications.     

CoFe2O4/NiFe2O4 S-scheme composite for photocatalytic decomposition of antibiotic contaminants

Keeping in view of the hazardous application of tetracycline hydrochloride antibiotic, an efficient CoFe₂O₄/NiFe₂O₄ heterojunction photocatalyst has been prepared hydrothermally by combining CoFe₂O₄ and NiFe₂O₄ nanoplates. The CoFe₂O₄/NiFe₂O₄ composite with the improved photocatalytic activity can be employed for removal of tetracycline hydrochloride antibiotic, comparing to the bare CoFe₂O₄ and NiFe₂O₄. The optimized sample 5%-CoFe₂O₄/NiFe₂O₄ shows the high photocatalytic degrading tetracycline with 76.1% removal efficiency in 60 min. These improved photocatalytic activities are attributed to the extended visible light absorption and enhanced charge separation following S-scheme route as confirmed from photoluminescence and electrochemical studies. From the charge trapping experiments, it is confirmed that superoxide radical and holes in the valence band of NiFe₂O₄ with high thermodynamic energies are responsible for the photodegradation of the target pollutant. This work provides sufficient attention towards the preparation of low cost materials for the removal of highly hazardous pollutants being present in water.     

Gas-phase decomposition of formic acid over Fe2O3 catalysts

Fe_2O_3 catalyst samples were used for the decomposition of formic acid, in the gas phase. These catalysts were produced by calcination of Fe(NO_3)3· 9H_2O for 5 h, in air, in the temperature range 200-600C. All catalysts were characterized by temperature-programmed reduction (TPR) and X-ray diffraction (XRD). In addition, the surface area (S_BET) of these samples as well as the acidity and the basicity were determined. The catalytic gas-phase decomposition of formic acid was studied over Fe_2O_3 samples, at 200C, in a flow system. Carbon monoxide, carbon dioxide and formaldehyde were identified as the decomposition products using gas chromatography. A correlation between the acid-base characters of the used catalysts, and the rate of the decomposition products has been made. Also, a reaction mechanism is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis of a perfluorooctanoic acid molecularly imprinted polymer for the selective removal of perfluorooctanoic acid in an aqueous environment

Perfluorooctanoic acid (PFOA) contamination in the environment is a global problem. The aqueous phase is the main medium for PFOA because of its moderate solubility. Adsorption is a feasible way to remove PFOA because of its chemical and biological stability. In this study, a new type of molecularly imprinted polymer (MIP) for the selective adsorption of PFOA in aqueous solutions was synthesized by the precipitation polymerization method with PFOA as the template molecule after optimization. The adsorption kinetics and isotherms of the MIP adsorbent toward PFOA were studied, and the effects of the pH and cations on the adsorption were investigated with batch experiments. The results show that acrylamide (AAM) was the best functional monomer, and the optimal molar ratio of PFOA to AAM to ethylene glycol dimethacrylate (crosslinker) was 1:6:25. The optimized MIP adsorbent had a high affinity for PFOA, and the uptake percentage by the MIP adsorbent was 1.3–2.5 times that of the nonimprinted polymer (NIP) when PFOA existed alone. A maximum PFOA sorption capacity of 5.45 mg/g based on the Langmuir isotherm model was achieved with the MIP adsorbent. The MIP adsorbent exhibited a high selectivity for PFOA over competitive compounds (other perfluorinated alkyl carboxylic and sulfonic acids), whereas the NIP did not. Approximately 90% of the PFOA in the mixture was removed by the MIP adsorbent; this was 18 times that of the NIP. Moreover, the regenerability of the MIP adsorbent was confirmed in five sequential adsorption–desorption cycles without a significant reduction in the PFOA uptake. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43192.     

淀粉燃料对多孔Al_2O_3-ZrO_2(Y_2O_3)陶瓷性能的影响

为了提高多孔Al2O3-ZrO2(Y2O3)陶瓷的强度,以尿素和淀粉为燃料,用低温燃烧法合成活性较高的Al2O3-ZrO2(Y2O3)复合粉体,并用此粉体制备了多孔Al2O3-Zr O2(Y2O3)陶瓷,研究燃烧前驱体中淀粉的外加量(质量分数分别为0、15%、25%、35%、45%、55%)对多孔陶瓷显气孔率、抗折强度和显微结构的影响。结果表明:与尿素为燃料相比,以尿素和淀粉为燃料能提高复合粉体的烧结活性,有效改善多孔陶瓷的显微结构,提高多孔陶瓷的抗折强度。     

Polycrystalline In2O3 and In2O3/Y2O3 photoanodes

Single crystal In₂O₃ shows promise as a photoanode for the decomposition of water. Because of various difficulties in the preparation of the single crystal material, two simple techniques were developed for the preparation of polycrystalline In₂O₃ anodes. One method involves the thermal decomposition of the nitrate while the other utilizes the chemical vapour deposition technique. Voltammograms and photoresponse spectra of these anodes are compared to the single crystal material. Among other observations, it is noted that the quantum efficiencies of the thermally decomposed films are comparable to the single crystal material. It is also shown that the on-set potential can be shifted to more negative values by forming the mixed oxide In₂O₃/Y₂O₃.     

Synthesis of nano-sized indium oxide (In2O3) powder by a polymer solution route

Indium oxide (In₂O₃) is a n-type semiconductor with various applications in thin film coatings, on the basis of its optical properties, and in gas sensing equipment, due to its high sensitivity to various oxides such as CO_x and NO_x. In this study, a synthesis process for obtaining In₂O₃ nanoparticles is examined. The precursor used is indium nitrate hydrate (InN₃O₉·H₂O) because of its high solubility in water. By dissolving the nitrate salt in a PVA (polyvinyl alcohol) solution, the precursor is dispersed homogeneously, which reduces the agglomeration of the resulting powder. Calcination at a low temperature of 200–250 °C burns out the organic materials of the PVA with NO_x gas emission and allows the oxidation of the indium, resulting in indium oxide nanoparticles. The influence of the PVA solution characteristics and the heat treatment temperature on the powder morphology and size was analyzed by using SEM, TEM, XRD, TGA/DSC, and four point BET for a specific surface area analysis. The measured specific surface area varies from 3 m²/g to 76 m²/g depending on the calcination temperature, and the particle size of the synthesized powders is under 10 nm for the samples heat treated at 300 °C.     

Preparation and characterization of indium based complex perovskites-Pb(In1/2Nb1/2)O3 (PIN), Ba Ba(In1/2Nb1/2)O3 (BIN), and Ba(In1/2Nb1/2)O3 (BIT)

The processing of order-disorder perovskites Ba(In_1/2Nb_1/2)O₃ (BIN), Ba(In_l/2Ta_1/2)O₃ (BIT), and the lead analogue Pb(In_1/2Nb_1/2)O₃ (PIN) was investigated with an emphasis on improving and expanding our knowledge of microwave dielectric materials. Both BIN and BIT were shown to be paraelectric perovskites. The processing and annealing of PIN were related to the perovskite and its transformation to pyrochlore. Dielectric and physical characteristics were examined by X-ray diffraction profiles (XRD), scanning electron microscopy (SEM), and dielectric behavior. Attempts to enhance B-site cation order in PIN by thermal annealing were unsuccessful due to a pyrochlore formation.     

Synthesis of S-rich flower-like Fe2O3-MoS2 for Cr(VI) removal

A novel Fe₂O₃-MoS₂ nanocomposite was synthesized directly via the solvothermal method. Scanning electron microscopy (SEM) results showed the as-prepared Fe₂O₃-MoS₂ had a uniform 3D blooming flower-like nanostructure with a MoS₂ substrate. The high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) confirmed the Fe₂O₃ nanostructures were well-dispersed on the surface of the layered MoS₂. The elemental mapping results revealed Fe, O, Mo and S elements coexisted in the Fe₂O₃-MoS₂ nanocomposite. X-ray photoelectron spectroscopy (XPS) results displayed an S-rich MoS₂ structure had been formed in the Fe₂O₃-MoS₂ nanocomposite. As expected, the S-rich Fe₂O₃-MoS₂ nanocomposite had better photocatalytic performance on Cr(VI) reduction than that of bare Fe₂O₃, MoS₂ and TiO₂ P25.     

Synthesis of porous Al2O3/ZrO2 nanocomposites by chemical vapour deposition

Al₂O₃/ZrO₂ one-dimensional nanocomposite structures were synthesised by chemical vapour deposition using Al₂O₃ nanowires and a ZrCl₄ powder source at a temperature of 800?°C and a pressure of 130?Pa. The samples were characterised using X-ray diffraction, the scanning electron microscopy, the transmission electron microscopy, and N₂ adsorption–desorption. The results revealed that Al₂O₃/ZrO₂ composite nanowires coated with surface-embedded ZrO₂ nanocrystals were formed and that the ZrO₂ macroporous and mesoporous structures changed as the ZrO₂ deposition time increased. The pore structure and surface area were also elucidated from the N₂ adsorption–desorption measurements.     

2-(咪唑并[1,2-a]吡啶-3-基)乙酸的制备

研究了一种用于治疗骨质疏松症药物的关键中间体米诺膦酸的制备方法。实验以二乙氧基膦酰乙酸乙酯和2,2-二甲氧基乙醛为起始原料,经维蒂希-霍纳反应、水解、环合、水解4步制备得到标题化合物。其熔点与1HNMR和文献报道的结果一致,总收率87.5%(以2-氨基吡啶计)。该方法克服了文献报道的工艺缺陷,与现有技术相比,后处理更简单,更适合工业化生产。     

Formation of closed pore structure in CaO-MgO-Al2O3-SiO2 (CMAS) porous glass-ceramics via Fe2O3 modified foaming for thermal insulation

Due to the low density, low thermal conductivity and low water absorption, porous glass-ceramics have demonstrated excellent performance for thermal insulation. Closed pore structure can greatly reduce the thermal conductivity and convection as well as achieve high mechanical strength. However, yet it is difficult to realize closed pore structure due to the critical preparation condition. Here we use Fe₂O₃, which is the by-product of copper tailings, to optimize the pores structures of the porous glass-ceramics and facilitate the formation of uniform closed pore structure. The porous glass-ceramics were prepared by melting-quenching method, followed by sufficiently foaming through powder sintering route with SiC powders as foaming agent. The foaming process, micro structure, pore structure and thermal insulation performance were directly observed by heating microscope, scanning electron microscope (SEM), X-ray computed tomography and infrared thermal imager. The results show that the addition of Fe₂O₃ modified the depolymerization degree of the glass network and increased the numbers of non-bridged oxygen, decreasing the foaming temperature. The resultant closed pore structure showed a better thermal insulating performance than open pore structure. Accordingly, we achieved a low thermal conductivity of 0.19 W·m^?1·K^?1 with the highest specific strength of 19.55 MPa·g^?1·cm^?3 based on closed pore structure.     

Synthesis of porous poly(hydroxamic acid) from poly(ethyl acrylate-co-divinylbenzene)

Summary Porous poly(hydroxamic acid) resins were prepared by suspension polymerization of poly(ethyl acrylate-co-divinylbenzene) followed by the reaction with hydroxylamine via nucleophilic substitution. Various degree of dilution and crosslinking ratio were applied to obtain suitable material for use as a chelating polymer. The effects of degree of dilution and crosslinking ratio on the surface morphology, hydroxamic acid group content, and apparent density were investigated in detail.     

Enhanced photocatalytic performance of hierarchical Bi2O2CO3 microflowers by Fe(III) modification

Hierarchical Bi₂O₂CO₃ microflowers with Fe(III) clusters grafted on the surfaces were synthesized through a simple impregnation technique. The as-prepared samples were characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and UV–vis diffuse reflectance spectroscopy. The photocatalytic activity was evaluated by the decomposition of methyl orange in an aqueous solution under visible-light (λ>420 nm) and simulated sunlight illumination. The results show that the Fe(III) clusters are just deposited on the surfaces rather than doped in the lattices of Bi₂O₂CO₃. It is found that the morphologies and crystal structures of Bi₂O₂CO₃ microflowers were not changed after modification of Fe(III) clusters. The photocatalytic activities of the Fe(III)-modified Bi₂O₂CO₃ were markedly increased by the modification of Fe(III) clusters under visible light and simulated sunlight irradiation. The enhanced photocatalytic performance can be attributed to the direct interfacial charge transfer from the valence band of Bi₂O₂CO₃ to the surface Fe(III) clusters, which offer a new channel for the efficient generation of the hole in the valence band of Bi₂O₂CO₃ substrate.     

Synthesis and photocatalytic properties of H2La2Ti3O10/TiO2 intercalated nanomaterial

H₂La₂Ti₃O₁₀/ TiO₂ intercalated nanomaterial was fabricated by successive intercalation reactions of H₂La₂Ti₃O₁₀ with n-C₆H₁₃NH₂/C₂H₅OH mixed solution and acid TiO₂ sol, followed by irradiating with a high-pressure mercury lamp. The intercalated materials possess a gallery height of 0.46 nm and a specific surface area of 31.58 m²·g⁻¹, which indicate the formation of a porous material. H₂La₂Ti₃O₁₀/TiO₂ shows photocatalytic activity for the decomposition of organic dye under irradiation with visible light and the activity of TiO₂ intercalated material was superior to the unsupported one.     

配合物Zn(3-apac)2(H2O)2的合成与表征

以3-氨基吡嗪-2-羧酸为配体合成了一个锌的单核配合物Zn(3-apac)2(H2O)21(3-apac:3-氨基吡嗪-2-羧酸),并利用元素分析,红外光谱,单晶X-射线衍射以及热重分析对配合物1进行了表征.晶体学数据:单斜晶系,C2/c空间群,a=0.79137nm,b=1.26517nm,c=1.3631nm,α=...     

Synthesis,characterization, photocatalytic and antibacterial properties of copper Ferrite/MXene (CuFe2O4/Ti3C2) nanohybrids

The synthesis of CuFe₂O₄/MXene nanohybrids was carried out via an ultrasonication approach. The prepared composite material exhibited an outstanding photocatalytic performance and antibacterial activity compared to individual CuFe₂O₄ (CF) and MXene. The CF nanonuts (Nns) assisted the reduced aggregation of MXene layers. The structural and morphological analysis of the presented nanohybrids were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FT-IR), Electrochemical impedance spectroscopy (EIS), and ultraviolet (UV)-visible spectroscopy. The obtained sheet-to-sheet linkage provided an opportunity for the degradation of organic dyes. The photocatalyst CF/MXene nanohybrids exhibited 4.5-fold higher photocatalytic activity than pristine CF. The mechanism of degradation of methylene blue dye by CF/MXene was explained through kinetic studies. This work will offer significant scientific contributions to researchers working on water desalination.     

Co3O4-Bi2O2CO3催化剂的制备及其光催化性能

以Bi(NO₃)₃·5H₂O、Co(CH₃COO)₂·4H₂O为原料,采用化学沉淀-水热法制备了Co₃O₄-Bi₂O₂CO₃异质结构复合半导体光催化剂,并通过X射线衍射仪（XRD）、扫描电镜（SEM）、X射线光电子能谱（XPS）、紫外可见漫反射光谱（DRS）、荧光光谱（PL）等手段对所合成的复合型催化剂进行了理化性能表征。研究结果表明：引入Co₃O₄没有改变Bi₂O₂CO₃物相结构,但促进了Bi₂O₂CO₃ 对可见光的吸收能力,提高了Bi₂O₂CO₃表面吸附氧物种的数量,抑制了光生载流子复合。复合光催化剂对罗丹明B（RhB）的光催化脱色实验显示引入Co₃O₄能够明显提高Bi₂O₂CO₃催化剂的光催化脱色能力。尤其是Co₃O₄引入量为0.6%的Co₃O₄-Bi₂O₂CO₃样品对罗丹明B染料的光催化脱色率可达到97%（模拟日光照射30min）。本文为复合型光催化剂制备提供了简单易行的技术路线,制备的新型半导体复合光催化剂Co₃O₄-Bi₂O₂CO₃在环境净化方面表现出了较好的应用前景。