MICROPOROUS AND MESOPOROUS MATERIALS
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2019
·
IF 4.182
Junjie Zhou,Chen Zhou,Kai Xu,Jürgen Caro,Aisheng Huang
Thin, phase-pure and well inter-grown zeolite FAU membranes are synthesized upon modifying the tubular supports using 3-aminopropyltriethoxysilane (APTES). The as-synthesized zeolite FAU membranes are evaluated in the dewatering of dimethyl carbonate (DMC) by pervaporation . Due to the large pore size (0.74 nm) and high hydrophilicity of zeolite FAU, the prepared zeolite FAU membranes exhibit high water flux and separation performance for the separation of H 2 O and DMC. With increasing the temperature or water content in the feed, the zeolite FAU membranes show higher flux while maintaining high separation factors. Further, for dewatering of 10 wt% H 2 O/90 wt% DMC mixtures at 353 K in a lab device, the DMC concentration in the feed side reaches 99% after continuously dewatering over 9 h. Besides, the zeolite FAU membranes are also successfully prepared on commercial tubular size of 80 cm and 100 cm long α-Al 2 O 3 tubes. The obtained membranes show high separation performance for the dewatering of DMC solution as well. The high-performance zeolite FAU membrane offers great potential for dewatering of DMC solutions in industry.
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ANALYTICA CHIMICA ACTA
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2019
·
IF 5.256
Zhongtang Wang,Zhaoya Huang,Yun Xie,Zhaoyi Tan
Plutonium has been extensively studied in the environment, for the purpose of radiological assessment, environmental behavior study and nuclear emergency response. To determine Pu isotopes in environmental soil and sediment, a novel analytical method was established in this study using a new type of extraction resin, TK200 resin. Firstly an investigation was performed to study the extraction behaviors of Pu, U, Th, Hg, Tl, Pb, Bi and Hf on TK200 resin. On the basis of the results, a new chromatographic procedure was then proposed to separate Pu from the elements that interfere the accurate determination of Pu isotopes by mass spectrometry. Owing to the excellent separation efficiency between Pu and interfering elements (IEs) of the developed procedure, high decontamination factors (DFs) were obtained for IEs, e.g. the DF(U) (>7.5 × 10 7 ) was the highest reported value. The separation procedure was finally combined with HNO 3 leaching, CaF 2 /LaF 3 coprecipitation and sector field-inductively coupled plasma mass spectrometry (SF-ICPMS) measurement to establish a complete method. The established method was evaluated by analyzing four standard reference materials (soil, sediment), and the results showed that both 239+240 Pu activity and 240 Pu/ 239 Pu isotopic ratio were accurately determined, with stable and high Pu chemical recoveries (81–91%). The whole analytical method only took about 15 h, and the limits of detection were calculated to be 0.13–0.24 fg g −1 for Pu isotopes (for 2 g soil or sediment), guaranteeing the rapid determination of ultra-trace level Pu in soil and sediment samples.
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Progress in Natural Science-Materials International
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2019
·
IF 3.31
Xinyang Jiao,Xiaoping Cai,Gao Niu,Xuanru Ren,Xueqin Kang,Peizhong Feng
Porous TiAl 3 intermetallics were synthesized from Ti-75 at.% Al elemental powder mixtures using an energy-saving and rapid reactive method of thermal explosion (TE). The results demonstrated that the actual temperature of the compact climbed rapidly from 673 °C to 1036 °C within 24 s, indicating that an obvious TE reaction occurred during sintering process. The video graphs suggested that the TE in Ti–Al system behaved instant occurrence and overall heating whether from axial or radial direction. The silver wires and NaCl particles that pressed on the surface of the sample disappeared due to the heavy heat released during TE reaction. Only pure TiAl 3 phases were synthesized in TE products and the open porosity of 55.4% was easy to obtain. After high-temperature treatment at 1000 °C, large amounts of sintering-neck formed and then improved the compressive strength of porous TiAl 3 materials. Moreover, the mass gain curve of porous TiAl 3 intermetallics oxidized at 650 °C for 120 h exhibited the parabolic oxidation rate law. XPS analysis confirmed that the strong O 1s peak was 531.4 eV which was the typical binding energy of Al 2 O 3 . Therefore, the excellent oxidation resistance of porous TiAl 3 foams would be considered as good candidate materials for prolonging the service life at high temperatures.
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Materials
·
2019
·Vol. 12
·期 19
·3097
·
IF 2.972
Hailiang Du,Ning Tan,Li Fan,Jiajie Zhuang,Zhichao Qiu,Yanhua Lei
The diffusion coatings were deposited on commercially pure Ti and Ti-6Al-4V alloy at up to 1000 °C for up to 10 h using the pack cementation method. The pack powders consisted of 4 wt% Al (Al reservoir) and 4 wt% NH4Cl (activator) which were balanced with Al2O3(inert filler). The growth kinetics of coatings were gravimetrically measured by a high precision balance. The aluminised specimens were characterised by means of scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). At the early stages of deposition, a TiO2(rutile) scale, other than aluminide coating, was developed on both materials at <900 °C. As the experimental temperature arose above 900 °C, the rutile layer became unstable and reduced to the low oxidation state of Ti oxides. When the temperature increased to 1000 °C, the TiO2scale dissociated almost completely and the aluminide coating began to develop. After a triple-layered coating was generated, the coating growth was governed by the outward migration of Ti species from the substrates and obeyed the parabolic law. The coating formed consisted of an outer layer of Al3Ti, a mid-layer of Al2Ti and an inner layer of AlTi. The outer layer of Al3Ti dominated the thickness of the aluminide coating.Keywords:diffusion coating;aluminide;pack cementation;Ti;Ti-6Al-4V;mechanism
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ADVANCED FUNCTIONAL MATERIALS
·
2019
·Vol. 29
·期 46
·1905694
·
IF 15.621
Lin Yang,Chunxiang Dall'Agnese,Yohan Dall'Agnese,Gang Chen,Yu Gao,Yoshitaka Sanehira,Ajay Kumar Jena,Xiao-Feng Wang,Yury Gogotsi,Tsutomu Miyasaka
MXenes are a large and rapidly expanding family of 2D materials that, owing to their unique optoelectronic properties and tunable surface termination, find a wide range of applications including energy storage and energy conversion. In this work, Ti 3 C 2 T x MXene nanosheets are applied as a novel type of electron transport layer (ETL) in low-temperature processed planar-structured perovskite solar cells (PSCs). Interestingly, simple UV-ozone treatment of the metallic Ti 3 C 2 T x that increases the surface Ti O bonds without any change in its bulk properties such as high electron mobility improves its suitability as an ETL. Improved electron transfer and suppressed recombination at the ETL/perovskite interface results in augmentation of the power conversion efficiency (PCE) from 5.00% in the case of Ti 3 C 2 T x without UV-ozone treatment to the champion PCE of 17.17%, achieved using the Ti 3 C 2 T x film after 30 min of UV-ozone treatment. As the first report on the use of pure MXene layer as an ETL in PSCs, this work shows the great potential of MXenes to be used in PSCs and displays their promise for applications in photovoltaic technology in general.
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International Journal of Applied Ceramic Technology
·
2019
·Vol. 17
·期 2
·778-789
·
IF 1.074
Weihua Chen,Jiancheng Tang,Xingwang Shi,Nan Ye,Zhihao Yue,Xinghao Lin
High-purity titanium aluminum carbide (Ti 3 AlC 2 ) powders were synthesized by a microwave sintering method using different titanium sources as raw materials. The prepared products were characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results indicated that the synthesized Ti 3 AlC 2 powders have high purity (97.5%) and even distribution of the grain size when using a 3TiH 2 /1.2Al/2C mixture as raw materials when the microwave sintering temperature and time were 1300°C and 30 minutes, respectively. The formation mechanism of the Ti 3 AlC 2 is described as proceeding via four stages. The solid-phase reaction between titanium and aluminum occurs below the melting point of aluminum and the main product is a Ti 3 Al phase, which is an observed intermediate compound for the formation of Ti 2 AlC and Ti 3 AlC 2 . Thus, this study provides a beneficial approach to low-temperature synthesis of high-purity Ti 3 AlC 2 materials.
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JOURNAL OF POWER SOURCES
·
2020
·
IF 8.247
Yangyang Luo,Chenhui Yang,Yapeng Tian,Yi Tang,Xingtian Yin,Wenxiu Que
To enhance rate and cycle performances of nickel sulfide, the two-dimensional (2D) titanium carbide (Ti 3 C 2 , MXene) with good electrical conductivity and electrochemical stability is chosen as 2D supporting matrix for synthesizing nickel sulfide/delaminated Ti 3 C 2 (Ni–S/d-Ti 3 C 2 ) nanohybrids by a solvothermal method . The Ni–S/d-Ti 3 C 2 nanohybrids show a coexistence of Ni 3 S 2 and NiS with the characteristic peak of d-Ti 3 C 2 nanosheets , and have electroactive species-on-sheet structures. The optimal Ni–S/1d-Ti 3 C 2 nanohybrid delivers a high specific capacity of 840.4 C g −1 at 1 A g −1 with enhanced capacity retention of 64.3% at 30 A g −1 and an outstanding cycle performance, which are ascribed to an integration of d-Ti 3 C 2 nanosheets that can act as electric channels to accelerate electrons transport at interface of the nanohybrid during charge-discharge processes. An increased Ni 2+ content and BET surface area also contribute to redox reactions of Ni–S/1d-Ti 3 C 2 nanohybrid electrode. An asymmetric supercapacitor (ASC) fabricated by using the Ni–S/1d-Ti 3 C 2 nanohybrid as positive electrode and d-Ti 3 C 2 film as negative electrode exhibits an energy density of 20.0 Wh kg −1 at 0.5 kW kg −1 and a good cycling stability. Our work provides a favorable ingenuity for synthesizing advanced nickel sulfide-based nanohybrids and an alternative strategy of using 2D MXene as capacitive electrode for high-performance supercapacitors .
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JOURNAL OF AOAC INTERNATIONAL
·
2019
·Vol. 98
·期 1
·225-229
·
IF 1.201
Zhang Jing,Yong Xiaojing,Zhao Dongyan,Shi Qiuyi
The content of mononuclear Al (Ala%) changed with its determination time (ta) under different dosages of Ferron (7-iodo-8-hydroxyquinoline-5-sulfonic acid, [Ferron]), and the change of Ala% with [Ferron] at different ta was systematically investigated for the firsttime. Thus, the most appropriate ta was found with the optimal [Ferron]. Also, the judgment of the platform (flat or level portion) of the complete reaction on the absorption-time curve determined in the hydroxyl polyaluminum solution by Ferron timed spectrophotometry (Ferron assay) was first digitized. The time point (tb) of complete reaction between the medium polyaluminum (Alb)and Ferron reagent depended on the reaction extent, and time could not be used only to judge. Thus, the tb was accurately determined and reduced
to half of original, which improved the experiment efficiency significantly. The Ferron assay was completely optimized.
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CHEMICAL ENGINEERING JOURNAL
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2019
·
IF 8.355
Handong Jiao,Shuqiang Jiao,Shijie Li,Wei-Li Song,Haosen Chen,Jiguo Tu,Mingyong Wang,Donghua Tian,Daining Fang
Although rechargeable Al batteries attract interests due to their features of abundant Al source and high safety, the Al negative electrodes suffer from critical problems, including dendrite, corrosion, pulverization, non-recyclable Al wastes, etc. For addressing these challenges, here a novel liquid gallium is demonstrated for negative electrodes of Al batteries. The results show that the liquid gallium negative electrode enables the reversible alloying/dealloying between Al and Ga. Remarkably, the essential problems in the solid Al negative electrodes, including dendrite, corrosion and pulverization, would be well avoided attributed to the liquid state of the Ga electrode during cycling. In addition to the enhanced stable cycling performance, Ga negative electrode is also recyclable, allowing the cycled Ga for further presenting stable cycling in the re-assembled batteries, and which is helpful for its practical application. The results in the present work open a precedent way to develop the advanced negative electrode with dendrite-free, corrosion resistant and recyclable features and advantages for various types of rechargeable batteries.
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Catalysts
·
2019
·Vol. 9
·期 11
·944
·
IF 3.444
Jun Zhou,Yue Zhang,Song Li,Jing Chen
Heterogeneous catalysis often involves charge transfer between adsorbed molecules and the surface of catalyst, and thus their activity depends on the surface charge density. The efficiency of charge transfer could be optimized by adjusting the concentration of oxygen vacancies (Ov). In this work, hexagonal Ni(OH)2nanoparticles were initially synthesized by a hydrothermal process using aluminum powder as the sacrificial agent, and were then converted into 2D Ni/NiO nanocomposites through in situ reduction in hydrogen flow. The oxygen vacancy concentration in the NiO nanosheet could be well-controlled by adjusting the reduction temperature. This resulted in strikingly high activities for hydrogenation of nitrophenol. The Ni/NiO nanocomposite could easily be recovered by a magnetic field for reuse. The present finding is beneficial for producing better hydrogenation catalysts and paves the way for the design of highly efficient catalysts.Keywords:metal-oxide interaction;oxygen vacancy;hydrogenation;catalyst
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Materials Research Express
·
2019
·Vol. 6
·期 4
·045207
·
IF 1.449
Jing Liu,Yunzhu Ma,Wensheng Liu,Xiaolei Song,Shuwei Yao,Juan Wang,Ming Cheng,Chunlan Li
Precursor sol with a high solid content is significant for alumina fiber synthesis. In the present work, alumina precursor sols used for preparing alumina fibers were synthesized by dissolving aluminum powder (AP) into a mixture of formic acid, acetic acid and deionized water. The effects of preparation temperatures on solubility of AP, structure of the synthesized sols and gels were investigated. The reaction mechanism of hydrolysis and polymerization was also studied. Based on the reaction mechanism, alumina precursor sol with a high solid content was acquired through the adjustment of temperature. The results revealed that all the sols synthesized at the temperature from 85 °C to 115 °C consisted of polymers, linear oligomers and monomeric species. Colloidal particles presented spherical shape with a uniform size. However, AP cannot dissolve entirely at 85 °C and white precipitates (HO)Al(CH3COO)2 was produced at 105 °C and 115 °C. AP had the highest dissolution degree at 95 °C. A colorless and transparent alumina sol with the highest solid content was acquired at this temperature. The structure of concentrated gels was also discussed. It was revealed that network polymers increased when using sols synthesized at temperature above 105 °C, which were negative for spinning. Continuous green fibers were obtained successfully using the alumina sol prepared at 95 °C.
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ACS Applied Materials & Interfaces
·
2019
·
IF 8.456
Junfang Ding,Liping Li,Haorui Zheng,Ying Zuo,Xiyang Wang,Huixia Li,Shaoqing Chen,Dan Zhang,Xingliang Xu,Guangshe Li
Nanomaterials are widely used as redox-type reaction catalysts, while reactant adsorption and O2 activation are hardly to be promoted simultaneously, restricting their applications in many important catalytic fields such as preferential CO oxidation (CO-PROX) in H2-rich stream. In this work, an interface-enhanced Co3O4–CuCoO2 nanomesh was initially synthesized by a hydrothermal process using aluminum powder as a sacrificial agent. This nanomesh is systematically characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption, X-ray photoelectron spectroscopy, UV–vis absorption spectroscopy, Raman spectroscopy, X-ray absorption near-edge spectroscopy, hydrogen temperature-programmed reduction, and oxygen temperature-programmed desorption. It is demonstrated that the nanomesh possesses high-density nanopores, enabling a large number of CO adsorption sites exposed to the surface. Meanwhile, electron transfer from O2– to Co3+/Co2+ and the weakened bonding strength of Co–O bond at surfaces promoted the oxygen activation and redox ability of Co3O4. When tested as a catalyst for CO-PROX, this nanomesh with an optimized pore structure and a surface electronic structure, exhibits a strikingly high catalytic oxidation activity at low temperatures as well as a broader operation temperature window (i.e., CO conversion >99.0%, 100–200 °C) in the CO selective oxidation reaction. The present finding should be highly useful in promoting the quest for better CO-PROX catalysts, a hot topic for proton exchange membrane fuel cells and automotive vehicles.
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