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1.
A dense perovskite hollow fiber made of BaCoxFeyZrzO3−δ (BCFZ) was evaluated for the oxygen separation at low temperatures (400–500 °C). An oxygen permeation flux of 0.45 ml/min cm2 was obtained at 500 °C, which is the first oxygen permeation data reported at such low temperature so far. A degradation of the oxygen permeation at 500 °C was observed, but the oxygen fluxes through the hollow fiber membrane can be regenerated by thermal treatment at 925 °C for 1 h in air. Energy-dispersive X-ray spectroscopy (EDXS) shows that a strong element segregation occurs in the membrane during operation at low temperature. 相似文献
2.
Dr. Yongchao Jia Ning Guo Yuhua Zheng Hui Qiao Wenzhen Lv Qi Zhao Prof. Hongpeng You 《Chemphyschem》2012,13(14):3383-3387
A series of the solid‐solution phosphors Lu3?x?yMnxAl5?xSixO12:yCe3+ is synthesized by solid‐state reaction. The obtained phosphors possess the garnet structure and exhibit similar excitation properties as the phosphor Lu3Al5O12:Ce3+, but with an effectively improved red component in the emission spectrum. This can be attributed to the energy transfer from Ce3+ to Mn2+. Our investigation reveals that electric dipole–quadrupole interactions dominate the energy‐transfer mechanism and that the critical distance determined by the spectral overlap method is about 9.21 Å. The color‐tunable emissions of the Lu3?x?yMnxAl5?xSixO12:yCe3+ phosphor as a function of Mn3Al2Si3O12 content are realized by continuously shifting the chromaticity coordinates from (0.354, 0.570) to (0.462, 0.494). They indicate that the obtained material may have potential application as a blue radiation‐converting phosphor for white LEDs with high‐quality white light. 相似文献
3.
Dense ceramic samples BaCe0.9?xZrxSm0.10O3?α (x=0.10, 0.15, 0.20, 0.30) were obtained by heat‐treating the precursors prepared from a coprecipitation route. The phase structure, chemical stability and conduction behaviors of the ceramic samples have been investigated by X‐ray powder diffraction and alternating current impedance spectroscopy methods. All the ceramic samples displayed a single phase of orthorhombic perovskite. The samples with x≧0.20 were relatively stable after exposed to the flowing mixed gases: CO2 +H2O+N2 at 873 K for 12 h. Among the samples tested, the sample with x=0.20 exhibited both adequate conductivity and better chemical stability. The contribution of different charged species for x=0.20 sample to the conduction in wet hydrogen atmosphere was investigated by means of gas concentration cells. It was found that the sample of x=0.20 was almost a pure ionic conductor, and the ionic conduction was contributed mainly by proton and partially by oxide ion in wet hydrogen atmosphere at 773–1073 K. The ammonia synthesis at atmospheric pressure in an electrolytic cell based on the sample of x=0.20 was successfully conducted and the peak ammonia formation rate achieved 2.67×10?9 mol·s?1·cm?2 with direct current of 0.80 mA at 773 K. 相似文献
4.
Ursula Pachmayr Fabian Nitsche Dr. Hubertus Luetkens Sirko Kamusella Felix Brückner Dr. Rajib Sarkar Prof. Dr. Hans‐Henning Klauss Prof. Dr. Dirk Johrendt 《Angewandte Chemie (International ed. in English)》2015,54(1):293-297
Superconducting [(Li1?xFex)OH](Fe1?yLiy)Se (x≈0.2, y≈0.08) was synthesized by hydrothermal methods and characterized by single‐crystal and powder X‐ray diffraction. The structure contains alternating layers of anti‐PbO type (Fe1?yLiy)Se and (Li1?xFex)OH. Electrical resistivity and magnetic susceptibility measurements reveal superconductivity at 43 K. An anomaly in the diamagnetic shielding indicates ferromagnetic ordering near 10 K while superconductivity is retained. The ferromagnetism is from the iron atoms in the (Li1?xFex)OH layer. Isothermal magnetization measurements confirm the superposition of ferromagnetic and superconducting hysteresis. The internal ferromagnetic field is larger than the lower, but smaller than the upper critical field of the superconductor. The formation of a spontaneous vortex phase where both orders coexist is supported by 57Fe‐Mössbauer spectra, 7Li‐NMR spectra, and μSR experiments. 相似文献
5.
Ion‐Exchange‐Induced 2D–3D Conversion of HMA1−xFAxPbI3Cl Perovskite into a High‐Quality MA1−xFAxPbI3 Perovskite
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Ge Li Taiyang Zhang Nanjie Guo Feng Xu Dr. Xufang Qian Prof. Yixin Zhao 《Angewandte Chemie (International ed. in English)》2016,55(43):13460-13464
High‐quality phase‐pure MA1?xFAxPbI3 planar films (MA=methylammonium, FA=formamidinium) with extended absorption and enhanced thermal stability are difficult to deposit by regular simple solution chemistry approaches owing to crystallization competition between the easy‐to‐crystallize but unwanted δ‐FAPbI3/MAPbI3 and FAxMA1?xPbI3 requiring rigid crystallization conditions. Here A 2D–3D conversion to transform compact 2D mixed composition HMA1?xFAxPbI3Cl perovskite precursor films into 3D MA1?xFAxPbI3 (x=0.1–0.9) perovskites is presented. The designed Cl/I and H/FA(MA) ion exchange reaction induced fast transformation of compact 2D perovskite film, helping to form the phase‐pure and high quality MA1?xFAxPbI3 without δ‐FAPbI3 and MAPbI3 impurity. In all, we successfully developed a facile one‐step method to fabricate high quality phase‐pure MA1?xFAxPbI3 (x=0.1–0.9) perovskite films by 2D–3D conversion of HMA1?xFAxPbI3Cl perovskite. This 2D–3D conversion is a promising strategy for lead halide perovskite fabrication. 相似文献
6.
Efficient Visible‐Light‐Driven Z‐Scheme Overall Water Splitting Using a MgTa2O6−xNy /TaON Heterostructure Photocatalyst for H2 Evolution
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Shanshan Chen Yu Qi Dr. Takashi Hisatomi Qian Ding Tomohiro Asai Zheng Li Dr. Su Su Khine Ma Prof. Fuxiang Zhang Prof. Kazunari Domen Prof. Can Li 《Angewandte Chemie (International ed. in English)》2015,54(29):8498-8501
An (oxy)nitride‐based heterostructure for powdered Z‐scheme overall water splitting is presented. Compared with the single MgTa2O6?xNy or TaON photocatalyst, a MgTa2O6?xNy /TaON heterostructure fabricated by a simple one‐pot nitridation route was demonstrated to effectively suppress the recombination of carriers by efficient spatial charge separation and decreased defect density. By employing Pt‐loaded MgTa2O6?xNy /TaON as a H2‐evolving photocatalyst, a Z‐scheme overall water splitting system with an apparent quantum efficiency (AQE) of 6.8 % at 420 nm was constructed (PtOx‐WO3 and IO3?/I? pairs were used as an O2‐evolving photocatalyst and a redox mediator, respectively), the activity of which is circa 7 or 360 times of that using Pt‐TaON or Pt‐MgTa2O6?xNy as a H2‐evolving photocatalyst, respectively. To the best of our knowledge, this is the highest AQE among the powdered Z‐scheme overall water splitting systems ever reported. 相似文献
7.
Huaping Wang Juan Wang Yecan Pi Qi Shao Yueming Tan Xiaoqing Huang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2338-2342
Perovskite‐based electrocatalysts are one of the most promising materials for oxygen evolution reaction (OER), but their activity and durability are still far from desirable. Herein, we demonstrate that the double perovskite LaFexNi1?xO3 (LFNO) nanorods (NRs) can be adopted as highly active and stable OER electrocatalysts. The optimized LFNO‐II NRs with Ni/Fe ratio of 8:2 achieve a low overpotential of 302 mV at 10 mA cm?2 and a small Tafel slope of 50 mV dec?1, outperforming those of the commercial Ir/C. The LFNO‐II NRs also show high OER stability with slight current decrease after 20 h. The enhanced activity is explained by the improved surface area, tailored electronic structure as well as strong hybridization between O and Ni. 相似文献
8.
Huimei Duan Rui You Shutao Xu Zhaorui Li Kun Qian Tian Cao Weixin Huang Xinhe Bao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(35):12171-12176
Supported Pd catalysts are active in catalyzing the highly exothermic methane combustion reaction but tend to be deactivated owing to local hyperthermal environments. Herein we report an effective approach to stabilize Pd/SiO2 catalysts with porous Al2O3 overlayers coated by atomic layer deposition (ALD). 27Al magic angle spinning NMR analysis showed that Al2O3 overlayers on Pd particles coated by the ALD method are rich in pentacoordinated Al3+ sites capable of strongly interacting with adjacent surface PdOx phases on supported Pd particles. Consequently, Al2O3‐decorated Pd/SiO2 catalysts exhibit active and stable PdOx and Pd–PdOx structures to efficiently catalyze methane combustion between 200 and 850 °C. These results reveal the unique structural characteristics of Al2O3 overlayers on metal surfaces coated by the ALD method and provide a practical strategy to explore stable and efficient supported Pd catalysts for methane combustion. 相似文献
9.
Template‐Free Preparation of Volvox‐like CdxZn1−xS Nanospheres with Cubic Phase for Efficient Photocatalytic Hydrogen Production
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Hangyue Zhou Prof. Qingyun Liu Prof. Weimin Liu Prof. Jiechao Ge Dr. Minhuan Lan Prof. Chao Wang Prof. Jianxin Geng Prof. Pengfei Wang 《化学:亚洲杂志》2014,9(3):811-818
Volvox‐like CdxZn1?xS solid solutions with a cubic zinc blend structure were synthesized through a template‐free ethylene glycol process. Cd(Ac)2 ? 2 H2O, Zn(Ac)2 ? 2 H2O, and thiourea are used as the starting materials and dissolved in ethylene glycol. These reaction precursors and solvent not only contributed to control over the formation of the volvox‐like spherical geometry, but also exerted vigorous domination for existence of cubic‐phase CdxZn1?xS nanostructures. As‐prepared volvox‐like CdxZn1?xS nanospheres have a diameter of around 100 nm with extensional shells. These samples show excellent photocatalytic H2 evolution activity from water splitting under visible‐light irradiation without any cocatalyst or scaffolding, owing to their tunable band gap, cubic zinc blend structure, and unique hierarchical porous structure with a high surface area (as high as 95.2 m2 g?1). 相似文献
10.
Exploring advanced electrocatalysts for electrocatalytic hydrogen evolution is highly desired but remains a challenge due to the lack of an efficient preparation method and reasonable structural design. Herein, we deliberately designed novel Ag/WO3?x heterostructures through a supercritical CO2‐assisted exfoliation‐oxidation route and the subsequent loading of Ag nanoparticles. The ultrathin and oxygen vacancies‐enriched WO3?x nanosheets are ideal substrates for loading Ag nanoparticles, which can largely increase the active site density and improve electron transport. Besides, the resultant WO3?x nanosheets with porous structure can form during the electrochemical cycling process induced by an electric field. As a result, the exquisite Ag/WO3?x heterostructures show an enhanced hydrogen evolution reaction (HER) activity with a low onset overpotential of ≈30 mV, a small Tafel slope of ≈40 mV dec?1 at 10 mA cm?2, and as well as long‐term durability. This work sheds light on material design and preparation, and even opens up an avenue for the development of high‐efficiency electrocatalysts. 相似文献
11.
SrNb0.1Co0.7Fe0.2O3−δ Perovskite as a Next‐Generation Electrocatalyst for Oxygen Evolution in Alkaline Solution
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Yinlong Zhu Prof. Wei Zhou Dr. Zhi‐Gang Chen Yubo Chen Dr. Chao Su Prof. Moses O. Tadé Prof. Zongping Shao 《Angewandte Chemie (International ed. in English)》2015,54(13):3897-3901
The perovskite SrNb0.1Co0.7Fe0.2O3?δ (SNCF) is a promising OER electrocatalyst for the oxygen evolution reaction (OER), with remarkable activity and stability in alkaline solutions. This catalyst exhibits a higher intrinsic OER activity, a smaller Tafel slope and better stability than the state‐of‐the‐art precious‐metal IrO2 catalyst and the well‐known BSCF perovskite. The mass activity and stability are further improved by ball milling. Several factors including the optimized eg orbital filling, good ionic and charge transfer abilities, as well as high OH? adsorption and O2 desorption capabilities possibly contribute to the excellent OER activity. 相似文献
12.
Robust SnO2−x Nanoparticle‐Impregnated Carbon Nanofibers with Outstanding Electrochemical Performance for Advanced Sodium‐Ion Batteries
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Dingtao Ma Dr. Yongliang Li Dr. Hongwei Mi Shan Luo Prof. Peixin Zhang Prof. Zhiqun Lin Prof. Jianqing Li Prof. Han Zhang 《Angewandte Chemie (International ed. in English)》2018,57(29):8901-8905
The sluggish sodium reaction kinetics, unstable Sn/Na2O interface, and large volume expansion are major obstacles that impede practical applications of SnO2‐based electrodes for sodium‐ion batteries (SIBs). Herein, we report the crafting of homogeneously confined oxygen‐vacancy‐containing SnO2?x nanoparticles with well‐defined void space in porous carbon nanofibers (denoted SnO2?x/C composites) that address the issues noted above for advanced SIBs. Notably, SnO2?x/C composites can be readily exploited as the working electrode, without need for binders and conductive additives. In contrast to past work, SnO2?x/C composites‐based SIBs show remarkable electrochemical performance, offering high reversible capacity, ultralong cyclic stability, and excellent rate capability. A discharge capacity of 565 mAh g?1 at 1 A g?1 is retained after 2000 cycles. 相似文献
13.
Lin Hu Ping Zhang Hao Zhong Xinrui Zheng Nan Yan Prof. Qianwang Chen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(47):15049-15056
A new facile strategy has been designed to fabricate spinel MnxCo3?xO4 porous nanocubes, which involves a morphology‐conserved and pyrolysis‐induced transformation of Prussian Blue Analogue Mn3[Co(CN)6]2 ? nH2O perfect nanocubes. Owing to the release of CO2 and NxOy in the process of interdiffusion, this strategy can overcome to a large extent the disadvantage of the traditional ceramic route for synthesis of spinels, and MnxCo3?xO4 with foamlike porous nanostructure is effectively obtained. Importantly, when evaluated as an electrode material for lithium‐ion batteries, the foamlike MnxCo3?xO4 porous nanocubes display high specific discharge capacity and excellent rate capability. The improved electrochemical performance is attributed to the beneficial features of the particular foamlike porous nanostructure and large surface area, which reduce the diffusion length for Li+ ions and enhance the structural integrity with sufficient void space for buffering the volume variation during the Li+ insertion/extraction. 相似文献
14.
Jessica J. Hong Liangdong Zhu Cheng Chen Longteng Tang Heng Jiang Bei Jin Trenton C. Gallagher Qiubo Guo Chong Fang Xiulei Ji 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(44):16057-16062
Plating battery electrodes typically deliver higher specific capacity values than insertion or conversion electrodes because the ion charge carriers represent the sole electrode active mass, and a host electrode is unnecessary. However, reversible plating electrodes are rare for electronically insulating nonmetals. Now, a highly reversible iodine plating cathode is presented that operates on the redox couples of I2/[ZnIx(OH2)4?x]2?x in a water‐in‐salt electrolyte. The iodine plating cathode with the theoretical capacity of 211 mAh g?1 plates on carbon fiber paper as the current collector, delivering a large areal capacity of 4 mAh cm?2. Tunable femtosecond stimulated Raman spectroscopy coupled with DFT calculations elucidate a series of [ZnIx(OH2)4?x]2?x superhalide ions serving as iodide vehicles in the electrolyte, which eliminates most free iodide ions, thus preventing the consequent dissolution of the cathode‐plated iodine as triiodides. 相似文献
15.
Resonant excitation energy transfer from [Cr(ox)3]3? to [Cr(bpy)3]3+ in the doped 3D oxalate networks [Rh1?xCrx(bpy)3][NaMIII1?yCry(ox)3]ClO4 (ox=C2O4?, bpy=2,2′‐bipyridine, M=Al, Rh) is due to two types of interaction, namely super exchange coupling and electric dipole–dipole interaction. The energy transfer probability for both mechanisms is proportional to the spectral overlap of the 2E→4A2 emission of the [Cr(ox)3]3? donor and the 4A2→2T1 absorption of the [Cr(bpy)3]3+ acceptor. The spin‐flip transitions of (pseudo‐)octahedral Cr3+ are known to shift to lower energy with increasing pressure. Because the shift rates of the two transitions in question differ, the spectral overlap between the donor emission and the acceptor absorption is a function of applied pressure. For [Rh1?xCrx(bpy)3][NaM1?yCry(ox)3]ClO4 the spectral overlap is thus substantially reduced on increasing pressure from 0 to 2.5 GPa. As a result, the energy transfer probability decreases with increasing pressure as evidenced by a decrease in the relative emission intensity from the [Cr(bpy)3]3+ acceptor. 相似文献
16.
A Dual‐Phase Ceramic Membrane with Extremely High H2 Permeation Flux Prepared by Autoseparation of a Ceramic Precursor
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Shunfan Cheng Yanjie Wang Libin Zhuang Dr. Jian Xue Dr. Yanying Wei Prof. Armin Feldhoff Prof. Jürgen Caro Prof. Haihui Wang 《Angewandte Chemie (International ed. in English)》2016,55(36):10895-10898
A novel concept for the preparation of multiphase composite ceramics based on demixing of a single ceramic precursor has been developed and used for the synthesis of a dual‐phase H2‐permeable ceramic membrane. The precursor BaCe0.5Fe0.5O3?δ decomposes on calcination at 1370 °C for 10 h into two thermodynamically stable oxides with perovskite structures: the cerium‐rich oxide BaCe0.85Fe0.15O3?δ (BCF8515) and the iron‐rich oxide BaCe0.15Fe0.85O3?δ (BCF1585), 50 mol % each. In the resulting dual‐phase material, the orthorhombic perovskite BCF8515 acts as the main proton conductor and the cubic perovskite BCF1585 as the main electron conductor. The dual‐phase membrane shows an extremely high H2 permeation flux of 0.76 mL min?1 cm?2 at 950 °C with 1.0 mm thickness. This auto‐demixing concept should be applicable to the synthesis of other ionic‐electronic conducting ceramics. 相似文献
17.
Origin and Location of Electrons and Protons during the Formation of Intermetalloid Clusters [Sm@Ga3−xH3−2xBi10+x]3− (x=0, 1)
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Dipl.‐Chem. Bastian Weinert B.Sc. Fabian Müller Dr. Klaus Harms Dr. Rodolphe Clérac Prof. Dr. Stefanie Dehnen 《Angewandte Chemie (International ed. in English)》2014,53(44):11979-11983
Reaction of [GaBi3]2? with [Sm(C5Me4H)3] yielded the first protonated ternary intermetalloid clusters [Sm@Ga3?xH3?2xBi10+x]3? ( 1 ; x=0,1). The presence of the Ga? H bonds and the transfer of electrons and protons during the formation of 1 were elucidated by a combination of experimental and quantum chemical methods, thereby rationalizing the role of the solvent ethane‐1,2‐diamine as a Brønsted acid. As an organic by‐product, we observed the previously unknown octamethylfulvene ( 2 ) upon C? C coupling of (C5Me4H)?. 相似文献
18.
Ram Krishna Hona Farshid Ramezanipour 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(7):2082-2085
Herein in we report the unprecedented catalytic activity of an iron‐based oxygen‐deficient perovskite for the oxygen‐evolution reaction (OER). The systematic trends in OER activity as a function of composition, defect‐order, and electrical conductivity have been demonstrated, leading to a methodical increase in OER catalytic activity: Ca2Fe2O6?δ<CaSrFe2O6?δ<Sr2Fe2O6?δ. Sr2Fe2O6?δ also has the highest electrical conductivity and a unique type of defect‐order. In conventional experiments using glassy carbon electrode, Sr2Fe2O6?δ shows better OER activity than the current state of the art catalysts, Ba0.5Sr0.5Co0.8Fe0.2O3?δ and RuO2. It also offers a high intrinsic electrical conductivity, which allows it to act as a catalyst without the need for glassy carbon electrode or carbon powder. Pure disks of this material exhibit an outstanding activity for OER, without any additives or need for electrode preparation. 相似文献
19.
Nanoscale iron‐doped zirconia solid‐solution aerogels are prepared via a simple ethanol thermal route using zirconyl nitrate and iron nitrate as starting materials, followed by a supercritical fluid drying process. Structural characteristics are investigated by means of powder X‐ray diffraction (XRD), thermal analyses (TG/DTA), N2 adsorption measurements and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The results show that the resulting iron‐doped solid solutions are metastable tetragonal zirconia which exhibit excellent dispersibility and high solubility of iron oxide. Further, when the Fe:(Fe+Zr) ratio x is lower than 0.10, all of the Fe3+ ions can be incorporated into ZrO2 by substituting Zr4+ to form Zr1?xFexOy solid solutions. Moreover, for the first time, an additional hydroxyl group band that is not present in pure ZrO2 is observed by DRIFTS for the Zr(Fe)O2 solid solution. This is direct evidence of Fe3+ ions incorporated into ZrO2. These Zr1?xFexOy solid solutions are excellent catalysts for the solvent‐free aerobic oxidation of n‐hexadecane using air as the oxidant under ambient conditions. The Zr0.8Fe0.2Oy solid‐solution catalyst demonstrates the best catalytic properties, with the conversion of n‐hexadecane reaching 36.2 % with 48 % selectivity for ketones and 24 % selectivity for alcohols and it can be recycled five times without significant loss of activity. 相似文献
20.
Amino‐Assisted Anchoring of CsPbBr3 Perovskite Quantum Dots on Porous g‐C3N4 for Enhanced Photocatalytic CO2 Reduction
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Man Ou Dr. Wenguang Tu Dr. Shengming Yin Weinan Xing Shuyang Wu Haojing Wang Shipeng Wan Prof. Dr. Qin Zhong Prof. Dr. Rong Xu 《Angewandte Chemie (International ed. in English)》2018,57(41):13570-13574
Halide perovskite quantum dots (QDs) have great potential in photocatalytic applications if their low charge transportation efficiency and chemical instability can be overcome. To circumvent these obstacles, we anchored CsPbBr3 QDs (CPB) on NHx‐rich porous g‐C3N4 nanosheets (PCN) to construct the composite photocatalysts via N?Br chemical bonding. The 20 CPB‐PCN (20 wt % of QDs) photocatalyst exhibits good stability and an outstanding yield of 149 μmol h?1 g?1 in acetonitrile/water for photocatalytic reduction of CO2 to CO under visible light irradiation, which is around 15 times higher than that of CsPbBr3 QDs. This study opens up new possibilities of using halide perovskite QDs for photocatalytic application. 相似文献