SOLID STATE PHENOMENA
·
2018
·
IF 0
Li Qian Cheng,Mei Feng,Kai Chen
Single crystalline lead-free (K, Na)NbO3 (KNN) nanostructures have attracted much attention for the high piezoelectricity and environmental compatibility. Especially, the plate-like KNN structures are supposed to be utilized in the synthesis of textured KNN-based ceramics. The KNN plate-like templates were prepared by a two-step molten salt reaction. The layered-perovskite Bi2.5Na3.5Nb5O18 (BNN5) was first prepared by using Bi2O3, Nb2O5, Na2CO3, NaCl as raw materials. The BNN5 precursors possess high aspect ratio with an average size of 15 - 20 μm in width and 0.5 - 1 μm in thickness. Then Bi element in the BNN5 was replaced by Na/K through topochemical reaction, and KNN plate-like products which have anisotropic crystal structure were fabricated. It should be emphasized that piezoresponse force microscopy (PFM) was used to confirm three-dimensional (3-D) morphology, while piezoelectric properties of single crystalline KNN platelets were acquired simultaneously. The as-synthesized KNN structures are expected to play an important role in the study of textured KNN ceramics. Meanwhile, the methodology investigated in this paper can also be applied for further fundamental studies on KNN system as well as other lead-free piezoelectric materials.
研究领域:
材料科学
·
无机化学
✓ 已验证
产品关联
DOI
FUEL
·
2023
·
IF 7.4
Xiaojian Wei,Yong Zhang,Hongzheng Zhu,Ming Yang,Jinbo Zhu
Using a high-speed motion acquisition system, the dodecane droplet size and the interface energy of the dodecane-solution interface during the collision between the dodecane droplet and the dodecane layer at different Na + concentrations were studied. The collision process is divided into three stages: Contact stage , Stretch stage and Attenuation amplitude stage . The size of the dodecane droplet gradually decreases as the Na + concentration increases, and the stretching time does too. The kinetic energy of the dodecane droplet, the surface energy of the dodecane-solution interface, and the net force of the dodecane droplet all decrease with an increase in Na + concentration, but the dodecane droplet rate of energy dissipation increases. The effect of Na + concentration on dodecane-solution interfacial tension is the main reason for the collision difference. The Na + added to the solution forms a hydration shell around it, weakening the interaction between water molecules at the dodecane-solution interface and within the solution, leading to reduced interfacial tension. The advancement of mineral flotation technology may benefit greatly from these findings.
研究领域:
化学工程
·
表面科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2024
·
IF 20.2
Jingyi Wang,Guangzhi He,Chunying Wang,Xudong Chen,Xiaofeng Liu,Yaobin Li,Wenpo Shan,Hong He
Modulating the electronic metal-support interaction (EMSI) is one of the effective means to promote catalytic activity because it can adjust the electron occupancy of the d -band of noble metals, further facilitating the activation of reactants. Herein, we prepared a Pt/SiO 2 catalyst with an ultralow Pt loading of 0.05% and found that its catalytic activity in HCHO oxidation outperformed that of the Pt/TiO 2 counterpart, owing to the EMSI effect between Pt and SiO 2 . On this basis, the alkali metal Na was used as a promoter, and the formation of highly active Pt-O x (OH)-Na clusters enabled the complete oxidation of HCHO at room temperature. With ultralow Pt loading, the Pt-Na/SiO 2 catalyst reduces the cost of practical application remarkably. In situ DRIFTS and DFT calculations confirmed that the reaction pathways were distinct on Pt/SiO 2 and Pt-Na/SiO 2 . Specifically, on Pt-Na/SiO 2 , the reaction follows the mechanism of the direct degradation of formate species with the assistance of active hydroxyls; while on Pt/SiO 2 , CO is the only intermediate formed by the dehydrogenation of HCHO, due to the lack of active hydroxyls. These findings provide new insights into the reaction pathway of HCHO oxidation.
研究领域:
催化化学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
Green Processing and Synthesis
·
2022
·Vol. 11
·期 1
·204-217
·
IF 3.97
Tao Liu,Lirui Mao,Facun Jiao,Chengli Wu,Mingdong Zheng,Hanxu Li
Flux, able to improve the ash fusibility, usually contains catalytic metal compounds. Unfortunately, the quantitative analysis of synergistic catalysis effects between different fluxing agents on coal gasification has not been investigated thoroughly. In this study, the effect of the kinds and content of Na/Ca-based fluxes on char gasification was investigated in thermogravimetry analyzer (TGA). The synergistic catalysis effects and mechanism between the two kinds of fluxes were also studied. Finally, based on the TGA tests, the kinetics models for char gasification with flux addition were developed. The results showed that all the four Na-based fluxes could increase the char reactivity. Na 2 CO 3 , which afforded the best activity, could increase the reactivity by 5.3 times when the content was 5%. The five Ca-based fluxes had a weaker catalysis effect compared with Na-based fluxes. CaCl 2 , exhibiting the best activity among the five Ca-based fluxes, could increase the reactivity by 2.3 times when the content was 5%. For composite fluxes, Na 2 CO 3 –CaO and Na 2 CO 3 –CaCO 3 had a remarkable synergistic effect, whereas others had less effect. Na 2 CO 3 could inhibit the aggregation of Ca, which might cause the synergistic effects between Na and Ca fluxes. The random pore model was more suitable to describe the catalytic gasification process.
研究领域:
能源科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2019
·
IF 5.128
Xiaowei Bai,Jian Li,Chenxi Jia,Jingai Shao,Qing Yang,Yingquan Chen,Haiping Yang,Xianhua Wang,Hanping Chen
In this study, a new-type of Na/Fe solid acid catalyst was synthesized to achieve efficient conversion of cellulose into furfural. The influence of Na/Fe mass ratios (0.05–2%), pyrolysis temperature (350–750 °C), and catalyst to cellulose ratio (0.2:1–20:1) was investigated through pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS), and the structure of Na/Fe catalyst was characterized with various approaches. Through scanning electron microscopy (SEM), the morphologies of the catalysts were found to exhibit rod-like, prismatic, spherical, and amorphous shapes with increasing Na/Fe. The results indicated that the selectivity of furfural increased with increasing Na/Fe ratio, and reached the highest value (61.4%) at a Na/Fe ratio of 1.42, after which it decreased with further increases in the Na/Fe ratio. Higher temperature and higher catalyst to biomass ratio are favorable for furfural formation, but exceedingly high temperature and catalyst to biomass ratio inhibit its formation. The maximum furfural yield could be achieved at 550 °C and catalyst to cellulose ratio of 10. The proposed catalytic pathway of cellulose pyrolysis for furfural is the promotion of the conversion of glucose monomers into dehydrated sugars such as LGO and DGP, which undergo secondary cracking to form furfural.
研究领域:
化学工程
·
生物质能
✓ 已验证
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2021
·Vol. 104
·期 8
·4119-4130
·
IF 3.784
Yu Huang,Liang Shu,Suwei Zhang,Zhen Zhou,Yue-Yu-Shan Cheng,Biaolin Peng,Lisha Liu,Yuanyuan Zhang,Xuping Wang,Jing-Feng Li
With the development of advanced electrical and electronic devices and the requirement of environmental protection, lead-free dielectric capacitors with excellent energy storage performance have aroused great attention. However, it is a great challenge to achieve both large energy storage density and high efficiency simultaneously in dielectric capacitors. This work investigates the energy storage performance of sol-gel-processed (K,Na)NbO 3 -based lead-free ferroelectric films on silicon substrates with compositions of 0.95(K 0.49 Na 0.49 Li 0.02 )(Nb 0.8 Ta 0.2 )O 3 -0.05CaZrO 3 - x mol% Mn (KNN-LT-CZ5- x mol% Mn). The appropriate amount of Mn-doping facilitates the coexistence of orthorhombic and tetragonal phases, suppresses the leakage current, and considerably enhances the breakdown strengths of KNN-LT-CZ5 films. Consequently, large recoverable energy storage density up to 64.6 J cm −3 with a high efficiency of 84.6% under an electric field of 3080 kV cm −1 are achieved in KNN-LT-CZ5-5 mol% Mn film. This, to the best of our knowledge, is superior to the majority of both the lead-based and lead-free films on silicon substrates and thus demonstrates great potentials of (K,Na)NbO 3 -based lead-free films as dielectric energy storage materials.
研究领域:
材料科学
·
能源存储
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry C
·
2019
·Vol. 7
·期 23
·6914-6923
·
IF 6.641
Yi-Xuan Liu,Hao-Cheng Thong,Chunlin Zhao,Qing Liu,Xingyu Xu,Ke Wang,Jing-Feng Li
The understanding of certain basic issues in (K,Na)NbO3 (KNN)-based systems is still missing, one of which being the influence of ZrO2 addition on the behaviors of KNN-based solid solutions at trace levels possibly introduced during the process of material preparation. Herein, KNN solid solutions with trace ZrO2 addition (0, 0.01, 0.05, and 0.1 mol%) were prepared by a normal sintering method. The dielectric permittivity and the piezoelectric coefficient d33 reach the maximum (εr = 497 and d33 = 139 pC N−1) with 0.1 mol% ZrO2 addition. Moreover, the microscopic results supported by PFM are in agreement with those from the macroscopic perspective. To establish the relationship among the ZrO2 addition contents, the induced defects and the properties of the solid solutions, a related defect model is proposed to support the experimental observation and the origin of induced defects is discussed. The results demonstrate that the properties of the KNN solid solutions can be closely affected by trace zirconia addition.
研究领域:
材料科学
·
陶瓷材料
✓ 已验证
DOI
高影响因子
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.
研究领域:
材料科学
·
催化化学
·
能源化学
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS COMMUNICATIONS
·
2019
·
IF 3.674
Feng Wang,GuoQin Qi,ChuanQi Zhang,HeCheng Ren,Hua Ma,Yu Guo
A series of Na-doped Pt/Al 2 O 3 catalysts with 0.2 wt% of Pt loading and 0–6 wt% Na loading was prepared to investigate the HCHO complete oxidation at room temperature. Powder XRD, BET and XPS were used to characterize the bulk structure and texture of catalysts, as well as the ratio of hydroxyl oxygen to lattice oxygen. A long-term catalyst stability test (50 h on reaction stream) was conducted under severe conditions of a large space velocity of 180,000 mL/h/g, a high HCHO concentration of 80 ppm and dry conditions (relative humidity of 0%). An appropriate amount of doped-Na (2 wt%) contributed to a remarkable improvement of activity and stability of the Na-doped 0.2 wt% Pt/Al 2 O 3 catalyst.
研究领域:
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
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.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
ChemSusChem
·
2025
·
IF 6.6
Fan Li,Yong-Feng Shen,Bin He,Wen-Cui Li
Dual-ion batteries are attracting much attention due to the joint participation of anions and cations in the energy storage process. However, this unique battery configuration imposes high demands on the cathode, which typically presents an inferior rate performance. Herein, we employ graphite in different microcrystalline sizes as cathodes, associated with high concentration electrolyte to construct sodium dual-ion batteries. The results of in-situ XRD and Raman evidence that the surface effect is enhanced by suitably small graphite microcrystals, where a greater surface involvement affords more electro-activated regions for the ions. Furthermore, the analysis of sputtering XPS confirms that the PF6- is accompanied by the co-intercalation of Na+ into cathodes by constructing the model of concentration effect, thus accelerating the kinetic process. In conclusion, the co-intercalation of PF6- together with Na+ is demonstrated under the influence of enhanced surface concentration effect in cathodes, and thus the cathodes exhibit a superior rate performance with a capacity of 103.6 mAh g-1 at a rate of 2 C and a rate retention of 94.8% even at 50 C. This work provides new insights to explain the mechanism of ion intercalation in dual-ion batteries and offers a perspective for the construction of high energy storage systems.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Xiaodong Yang,Xueqin Shao,Jin Tong,Jinfeng Zhou,Ying Feng,Rui Chen,Qiang Yang,Ye Han,Xizhen Yang,Lili Wang,Xuewen Ma,Zhongqing Fan,Zhi Song,Andrew R. Zimmerman,Bin Gao
Advanced clay sorbents have attracted widespread attentions for applications in environment remediation and pollution control. Here, a facile and environmentally-friendly approach to synthesizing a porous Na-bentonite/hickory-biochar composite sorbent from hickory waste biomass using hand-milling and carbon-bed pyrolysis was investigated. The sorbents, made using a range of clay/biomass ratios and at a range of temperatures, were characterized and examined for their ability to remove Eriochrome blue black R (EBBR) anionic organic dyes from aqueous solution. The composite sorbents showed increased microporosity and O-containing functional groups over the pyrolyzed bentonite control. The composite prepared with 10% biomass by weight, and at 600 °C had the greatest EBBR adsorption, and was best fit to Freundlich isotherm and intraparticle diffusion kinetics models. The modeled maximum EBBR sorption capacity of this composite (2020.5 mg g −1 , R2 adj = 0.92), which was attributed to the dispersion of bentonite particles over the biochar surface. These results show the bentonite/biochar composite to have great potential for use in environmental remediation applications.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）