JOURNAL OF RARE EARTHS
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2022
·
IF 4.632
Lingyun Li,Ziwei Zhou,Fazheng Huang,Senlin Peng,Yantang Huang,Guoqiang Wang,Xinxu Li,Fei-Fei Chen,Chengkai Yang,Xin-Xiong Li,Yan Yu
The Er 3+ doped double perovskite Ba 2 CaWO 6 crystal is a promising ratiometric thermometer based on the fluorescence intensity ratio (FIR) of transitions from 2 H 11/2 and 4 S 3/2 to the lowered 4 I 15/2 level. However, the Ca 2+ vacancy defect caused by the charge difference between rare-earth ions and the substituted alkaline-earth ions gives rise to the non-radiative probability and limits the thermal sensitivity. Here, the up-conversion luminescence and thermometric performance of Er 3+ , Yb 3+ doped Ba 2 CaWO 6 are tuned by tri-doping with alkaline ions. The Ca 2+ vacancy defect can be eliminated by the introduction of Na + , which occupies the Ca 2+ site when it is doped into Ba 2 CaWO 6 with Er 3+ and Yb 3+ . On the contrary, the doping of Cs + into Ba 2 CaWO 6 with Er 3+ and Yb 3+ enhances the defect concentration because it occupies the site of Ba 2+ . Thus, the tri-doping of Na + reduces the non-radiative probability and enhances the quantum efficiency of Er 3+ , leading to the improvement of the thermometric sensitivity of Ba 2 CaWO 6 . As a result, we get an excellent thermometric Ba 2 CaWO 6 :8%Yb 3+ ,3.5%Er 3+ ,6%Na + powder with a luminescence lifetime of 515 μs and maximum thermal sensitivity ( S r ) of 1.45%/K, which is more than three times higher than that of the BCWO:Er 3+ powder.
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JOURNAL OF NON-CRYSTALLINE SOLIDS
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2021
·
IF 3.531
Zhongtao Luo,Guangjun Yang,Meng Zhang,Yu Wang,Zhengkai Si,Yuandong Mu,Xiaohai Liu
The removal of Na + in the process of preparing silica aerogel with sodium silicate as the precursor is a very important and costly step. In this study, effects of residual Na + content (0∼3.0 wt.%) in the precursor on the properties of silica aerogel were investigated. The thermal conductivity, bulk density, porosity and hydrophobic of the aerogel were tested. And the action mechanism of Na + was discussed, based on the test results of pore structure, microscopic morphology, and chemical structure composition characterized by N 2 adsorption-desorption, SEM and FT-IR. The results showed that as the content of residual Na + increased, the thermal conductivity and density of the aerogel increased, and the porosity and hydrophobicity decreased. It may be the alkaline dissolution effect of Na + and the agglomerations of Na + block part of mesopores, but did not change the skeleton composition of the silica aerogels.
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高影响因子
FUEL
·
2021
·
IF 6.609
Mingquan Li,Aqsa Noreen,Yajie Fu,Cederick Cyril Amoo,Yujia Jiang,Xu Sun,Peng Lu,Ruiqin Yang,Chuang Xing,Shurong Wang
Directly synthesizing olefins from syngas using metal-zeolite composite catalysts has engrossed a lot of attention recently. Fe-based catalysts will be the most promising industrial candidates due to cost and availability constraints. In this work, we investigate the characteristics and Fischer-Tropsch activity of a novel Fe@Na-ZSM-5 composite for one-step conversion of syngas to higher olefins (C 5+ ). The in-situ crystallization mechanism induced Na in the ZSM-5 as a Fe-based promoter which realized 52.5 % selectivity for gasoline of which ∼ 70% were olefins. Additionally, the promotion by the Na ions enhanced the formation of Fe 5 C 2 phases which in turn favored C–C coupling, high gasoline and olefins selectivity. Na type zeolite (Na-Zeolite) offers a novel Na electron promoter, which participate immensely in the development of heterogenous catalyst and functional materials.
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高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2021
·Vol. 105
·期 1
·461-468
·
IF 3.784
Baoyu Deng,Yiming Ma,Tianxiang Chen,Huajing Wang,Jinfeng Lin,Cong Lin,Xiao Wu,Chunlin Zhao,Tengfei Lin,Min Gao,Xinghua Zheng,Changqing Fang
Dense (K, Na)NbO 3 ceramics are successfully fabricated via the cold sintering process at 350°C under a uniaxial pressure of 400 MPa for 4 h. Equimolar KOH and NaOH solutions were utilized as a transient alkaline flux. The microstructure and dielectric properties were studied in detail. Scanning electron microscope and the relative densities reveal dense structures of the ceramics. After post-annealing at 800°C for 1 h, the ceramics show good electrical performance. The relative dielectric permittivity is 829 (at 10 kHz) at room temperature, and the piezoelectric constant ( d 33 ) reaches up to 148 pC/N. The cold sintering technique with equimolar KOH and NaOH solutions as a transient alkaline flux endow KNN ceramics with excellent dielectric and piezoelectric properties, showing a potential way to fabricating other KNN-based ceramics at low temperature.
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高影响因子
COMPOSITES PART B-ENGINEERING
·
2021
·
IF 9.078
Saipeng Zhou,Mingming Hou,Yulong Sun,Wenzhe Zhao,Honglin Wang,Quanhui Guo,Xin Yu,Xinqi Ma,Junwei Zhao
Preparation of high-performance semiconductor photocatalysts is often considered to be the challenge and focus in dealing with water contaminations, and attracts numerous concerns and research interests nowadays. In this work, high-performance Z-scheme AgI/(Na,F) doped g-C 3 N 4 composites were synthesized by facile calcination and in-situ deposition methods and employed for ultrahigh-performance degradation of broad-spectrum antibiotics contaminants. The prepared (Na,F) doped g-C 3 N 4 showed narrower bandgaps, enhanced solar-light absorption, and highly improved visible-light photocatalytic performance. Besides, the strong combined interfaces between AgI nanoparticles and (Na,F) doped g-C 3 N 4 was contributing to visible-light harvesting and highly boosted charge separation of the samples, among which AgI/(Na,F)–CN-40% composite presented the best visible-light photocatalytic performance. The photocatalytic reaction rate constant of the AgI/(Na,F)–CN-40% composite was as high as approximately 0.2007 min −1 , which was 65.80 times of pristine g-C 3 N 4 and 3.60 times of AgI, mainly because of the construction of direct Z-scheme charge transfer pathways between AgI and (Na,F) doped g-C 3 N 4 . Finally, the radical scavenger experiments, possible degradation pathways , and photocatalytic mechanism were also proposed.
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ChemCatChem
·
2021
·Vol. 13
·期 13
·3027-3036
·
IF 5.686
Zhijian Wan,Youkun Tao,Hengzhi You,Xiang Zhang,Jing Shao
Graphical Ammonia decomposition : Ni nanoparticles with a mean size of ∼2.3 nm anchored on Na-ZSM-5 nanocrystals were prepared as a catalyst to effectively crack ammonia for CO x -free H 2 production. Ammonia has been increasingly recognised as an effective hydrogen carrier to produce clean hydrogen free of CO x emissions. This study reports the development of Ni-based catalysts to efficiently crack ammonia into hydrogen and nitrogen. A series of catalysts with different Ni loadings supported on Na-ZSM-5 zeolite nanocrystals were prepared with the assistance of 1,10-phenanthroline ligand. The coordination of Ni and the ligand led to the formation of uniform Ni nanoparticles with a mean size of ∼2.3 nm. These small Ni nanoparticles of the catalyst enabled a high activity in ammonia decomposition evaluated using a fixed-bed reactor. Using the zeolite support in its pristine sodium form provided the catalyst with desired basicity. This promotes a strong metal-support interaction, leading the catalyst to have high stability. The catalyst with 5 wt% Ni loading exhibited a high TOF of 3.51 s −1 with no performance degradation at 650 °C for 50 h.
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FUEL
·
2020
·
IF 5.578
Hongliang Li,Hua Han,Yue Wang,Xianshu Dong,Hongli Yang,Minqiang Fan,Yang Hu,Zeyu Feng
In coal beneficiation, the clean coal would be easily contaminated with the super fine montmorillonite particles coating on it. This interaction between coal (hydrophobic) and montmorillonite (hydrophilic) surfaces is the interactions between the asymmetric systems. Previous studies detected the force between the montmorillonite and graphite or between the montmorillonite mounted tip and coal substrate to represent the interactions between 001 surface and coal. However, there is still lack of experimental direct measurement on the interaction between montmorillonite 001 surface and coal macerals. In this study, proposes methods for determinine the interactions between coal macerals and 001 surface of Na-, K- and Ca- montmorillonite directly by using an atomic force microscope (AFM). The results indicate that the 001 surface of Na- and Ca- montmorillonite served as the chaotropic and kosmotropic surface when it is adjacent to coal surfaces, with an attractive force and repulsive force occurring between them, respectively. The 001 surface of K-montmorillonite served as the chaotropic surface and kosmotropic surface while it is close to liptinite and inertinite, respectively. This chaotropic or kosmotropic property of the surface is determined by the coordination number of the cations and wettability of the hydrophobic surface simultaneously.
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ADVANCED MATERIALS
·
2020
·Vol. 33
·期 3
·2006118
·
IF 27.398
Zhengping Ding,Chen Yang,Jian Zou,Shulin Chen,Ke Qu,Xiumei Ma,Jingmin Zhang,Jing Lu,Weifeng Wei,Peng Gao,Liping Wang
Fluorographites (CF x ) are ultrahigh-energy-density cathode materials for alkaline-metal primary batteries. However, they are generally not rechargeable. To elucidate the reaction mechanism of CF x cathodes, in situ transmission electron microscopy characterizations and ab initio calculations are employed. It is found that it is a two-phase mechanism upon K/Na/Li ion insertion; crystalline KF (crystalline NaF nanoparticles and amorphous LiF) is generated uniformly within the amorphous carbon matrix, retaining an unchanged volume during the discharge process. The diffusivity for K/Na/Li ion migration within the CF x is ≈2.2–2.5 × 10 –12 , 3.4–5.3 × 10 –12 , and 1.8–2.5 × 10 –11 cm 2 s –1 , respectively, which is comparable to the diffusivity of K/Na/Li ions in liquid-state cells. Encouraged by the in situ transmission electron microscopy (TEM) results, a new rechargeable all-solid-state Li/CF x battery is further designed that shows a part of the reversible specific discharge capacity at the 2nd cycle. These findings demonstrate that a solid-state electrolyte provides a different reaction process compared with a conventional liquid electrolyte, and enables CF x to be partly rechargeable in solid-state Li batteries.
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PubMed
高影响因子
ACS Applied Materials & Interfaces
·
2020
·
IF 8.758
Jinxu Qiu,Boran Chen,Hongying Hou,Xiaojuan Wang,Xiaoyang Liu,Zaihuan Li,Tingting Liu,Ruicong Chen,Shuai Wang,Bao Li,Dongmei Dai,Bao Wang
Because of their high reversible capacity and wide operation voltage window, P2-type layered transition metal oxides are considered as one type of potential cathode candidate for sodium-ion batteries. However, they still suffer from low kinetics, phase degeneration, and ambiguous mechanism of Na+ diffusion. Here, we synthesized a P2-type Na0.6Li0.07Mn0.66Co0.17Ni0.17O2 with a high Na+ diffusion performance by sintering a nanoplate-structural precursor with alkali metal salt and proposed a possible mechanism for improving Na+ diffusion. The as-prepared P2-type layered oxide presents a quasi-hexagon shape and demonstrates a discharge capacity of 87 mAh g–1 at a current density of 875 mA g–1 (5 C rate), twice that of the sample synthesized from a non-nanoplate particle precursor. Rietveld refinement and results of X-ray photoelectron spectroscopy reveal the probable mechanism that the expanded interplanar spacing along the c-axis orientation would facilitate Na+ diffusion during Na+ intercalation/deintercalation processes, and the expanded interplanar spacing may arise from a high oxidation state of transition metal ions.
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高影响因子
CARBOHYDRATE POLYMERS
·
2020
·
IF 7.182
Jin Liu,Shunyi Wang,Ke Xu,Zaibi Fan,Panpan Wang,Zijun Xu,Xueqin Ren,Shuwen Hu,Zideng Gao
A double crosslinked membrane based on chitosan/gelatin with controlled release properties was synthesized in aqueous system using potassium pyroantimonate and genipin as the ionic crosslinker and covalent crosslinker, respectively. The membranes were characterized using FT-IR, UV–vis spectra, and SEM. In addition, the thermal stability, contact angle, mechanical and controlled release properties were measured. Double-crosslinking significantly improved the hydrophobicity, thermal stability, and tensile strength of the membrane. The permeabilities of various plant nutrients, including urea and plant growth regulators (PGRs), were evaluated. Under the optimized conditions, the lowest flux (J) of urea was 2.89 mg/ (cm 2 ·h). Urea and PGR release were sustained for up to 3 and 10 days, respectively. The release of agrochemicals in this study followed the Weibull model, demonstrating the Na + -responsive and pH-responsive permeability of the films. This dual-responsive film has potential applications in salinized barrier soil, water treatment, separations, and other membrane applications.
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PubMed
高影响因子
MINERALS ENGINEERING
·
2020
·
IF 3.795
Richard M. Kasomo,Hongqiang Li,Huifang Zheng,Qian Chen,Xiaoqing Weng,Akisa D. Mwangi,Wu Ge,Shaoxian Song
In this paper, Na-CMC was studied as a depressant for almandine during flotation separation of rutile using cationic surfactant, octadecyl amine polyoxyethylene ether (AC1815) as a collector. Results of micro-flotation studies suggested that Na-CMC was considered as a selective depressant for almandine. Zeta potential and X-ray Photoelectron Spectroscopy (XPS) were used to elucidate the interaction mechanism between the minerals (rutile and almandine) and Na-CMC. The XPS analysis results show that there was both the chemical and hydrogen bonding in the interaction between almandine and Na-CMC. Zeta potential measurements indicate that, the adsorption of carboxylic groups on the almandine ferrous active sites, takes place with chemisorption which in turn depressed the almandine floatability. Contact angles results on the other hand shows that the floatability of almandine was adversely affected after being treated with Na-CMC, while the same depressant did not have any pronounced negative effect on the floatability of rutile.
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CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Chuangchuang Ruan,Mengmeng Fan,Yuewen Zhang,Hongzhang Song,Xin-Jian Li,Haoshan Hao
In this work, Bi 2 Ba 2 Co 2 O y + v wt% SiC ( v = 0.00, 0.025, 0.05, 0.1, 0.2) and Bi 1.975 Na 0.025 Ba 2 Co 2 O y + w wt% SiC ( w = 0.00, 0.025, 0.05, 0.1, 0.2) ceramic samples were synthesised. The increase in the carrier concentration caused by a small amount of Na element doping leads to a decrease in the resistivity and Seebeck coefficients. The lattice distortion caused by Na element doping decrease the sample thermal conductivity . After adding SiC nanoparticles , the resistivity can be reduced further. Especially more phonons are scattered by more grain boundaries, which leads to reduced thermal conductivity. The Seebeck coefficients increase slightly due to the low energy carrier scattering effect. Considering the influence of these two factors, dispersing SiC particles on the basis of Na element doping can effectively improve the thermoelectric performance of Bi 2 Ba 2 Co 2 O y -based samples. The ZT value of the Bi 1.975 Na 0.025 Ba 2 Co 2 O y + 0.1 wt% SiC sample reaches a maximum value of 0.21 at 923 K, 26.6% higher than the Bi 1.975 Na 0.025 Ba 2 Co 2 O y sample and 93% higher than the pure Bi 2 Ba 2 Co 2 O y sample.
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