Energy Technology
·
2018
·Vol. 7
·期 3
·1800747
·
IF 3.175
Pengjing Chen,Longang Tao,Jian Zhu,Guofeng Zhao,Ye Liu,Yong Lu
Indium oxide is as a promising catalyst for the hydrogenation of CO 2 to methanol. Previous studies mainly focused on the cubic-phase In 2 O 3 (C-In 2 O 3 ), but the hexagonal-phase In 2 O 3 (H-In 2 O 3 ) with a corundum structure has been rarely studied because of the difficulty in its synthesis. Herein, the morphology-controllable H-In 2 O 3 in situ structured onto a thin-felt Al 2 O 3 /Al-fiber is prepared by a facile mixed solvothermal method. The amount of H-In 2 O 3 is strongly dependent on the urea/In molar ratio during the mixed solvothermal synthesis. The optimal catalyst obtained at a urea/In ratio of 4.5 possesses the highest amounts of oxygen vacancy and strong basic site. Such catalyst achieves a turnover frequency of 47.8 h −1 (the number of CO 2 converted into methanol per oxygen vacancy site per hour) and is stable for at least 200 h, being capable of converting 4.4% CO 2 into methanol at a selectivity of 67.6% at 325 °C (or higher selectivity at the expense of conversion below 325 °C) with a methanol space time yield of 0.20 g MeOH g cat −1 h −1 . In contrast, the microfibrous-structured C-In 2 O 3 (prepared by the incipient wetness impregnation method) delivers a very low methanol selectivity of only 36.8% under identical reaction conditions. In situ Fourier transform infrared spectroscopy experiments reveal that the H-In 2 O 3 /Al 2 O 3 /Al-fiber catalyzes CO 2 -to-methanol conversion through formate intermediates.
研究领域:
催化化学
·
材料科学
·
能源化学
✓ 已验证
DOI
高影响因子
JOURNAL OF ELECTRONIC MATERIALS
·
2021
·Vol. 50
·期 4
·1949-1954
·
IF 1.938
Zhang Dunpu,Zhen Yue,Chang Qing,Zhang Hui
Highly crystalline β-NaLuF 4 :Ln 3+ microstructures were successfully prepared via a mixed NaCl-KCl flux cooling approach. The chemical reaction process and the formation mechanism have been carefully investigated by XRD, SEM, TEM and PL characterizations. Interestingly, as the reaction time is prolonged, the crystalline structure of NaLuF 4 changes from α-phase to β-phase, while the granule shape transfers from nanoparticles to solid microsheets then to porous microsheets. By altering the kinds of doped lanthanide ions, upconverting and downconverting luminescence with multi-colour outputs (red, green and blue) can be realized in β-NaLuF 4 :Ln 3+ (Ln = Yb, Er, Tm, Ce, Tb and Eu). This strategy is not only expected to meet the ever-increasing commercial demand, but also offers an alternative in synthesizing rare earth fluorides.
研究领域:
材料科学
·
光学
·
无机化学
✓ 已验证
DOI
高影响因子
OPTICAL MATERIALS
·
2023
·
IF 3.9
Xide Chang,Xu Dong,Xianhua Liu,Yindong Tong,Kaixiang Li,Zhenguo Li,Yiren Lu
Mixed-phase composites with an optimal phase ratio show greater light utilization than their monophasic counterparts. This approach can be applied to develop mixed-phase photochromic tungsten oxide (WO 3 ), which shows a rapid photoresponse and high-contrast coloring. Therefore, this paper optimized the phase ratio of hexagonal WO 3 ( h -WO 3 ·0.33H 2 O) and orthorhombic WO 3 ·H 2 O ( o -WO 3 ·H 2 O) to form a homojunction. To enhance its photochromism, nanostructured WO 3 was produced via a one-step hydrothermal strategy, in which its phase structure and morphology were controlled by regulating the reaction temperature during precursor synthesis. Various material characterization techniques were carried out to reveal the complex crystal nucleation and growth of phase junctions. h -WO 3 ·0.33H 2 O nanoparticles dominated the systems, while o -WO 3 ·H 2 O nanoblocks also appeared from 41.77 wt% to 56.50 wt% at a low hydrothermal synthesis temperature, producing a mixture of both polymorphs. The improved photochromic properties (from light yellow to black-green) of the mixed-phase WO 3 composite compared with pure h -WO 3 ·0.33H 2 O (from gray-white to dark gray) was attributed to the formation of a phase junction between h -WO 3 ·0.33H 2 O and o -WO 3 ·H 2 O. The photoelectrochemical results showed that this resulted in highly efficient charge carrier separation and transfer. The strong visual rendering of the black-green state may be useful for developing intelligent displays and similar devices.
研究领域:
材料科学
·
化学工程
·
光电材料
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry C
·
2013
·Vol. 2
·期 11
·2037-2044
·
IF 0
Xuesong Zhai,Shusen Liu,Yongling Zhang,Guanshi Qin,Weiping Qin
Ultrasmall upconversion (UC) nanoparticles with intense luminescence are quite desirable for in vitro and in vivo bioimaging. Herein, we report the successful synthesis of sub-10 nm hexagonal NaTm0.02Lu0.98−xYbxF4 nanocrystals via a high boiling solvent process. The sizes and phases of the crystals can be finely tailored by tuning the amounts of the ligands used (octadecylamine and sodium oleate) and the temperature. The intensity of the UC emission of the nanocrystals increases as the the relative content of Yb3+ ions increases from 20% to 98%, owing to improved near-infrared absorption and energy-transfer from Yb3+ to Tm3+. The experimental results indicate that hexagonal NaYbF4 is the best host for ultrasmall Tm3+-doped UC nanoparticles and shows great potential in biomedical applications.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
产品关联
DOI
RSC Advances
·
2021
·Vol. 11
·期 34
·20746-20751
·
IF 3.361
Raheel Ahmed Janjua,Obaid Iqbal,Muhammad Aqeel Ahmed,Abdullah A. Al-Kahtani,Sara Saeed,Muhammad Imran,Abdul Ghafar Wattoo
A comprehensive strategy has been developed to construct nano-sized homogeneous and heterogeneous core/shell structures of NaYF4 host. Synthesis conditions of cubic phase/α-NaYF4 and hexagonal phase/β-NaYF4 are discussed. Pure cubic NaYF4:Yb,Er nanocrystals were synthesized with different average sizes extending from 7 nm to 15 nm by varying the reaction time. Temperature and time thresholds of hexagonal nucleation were determined and utilized for controlled core/shell structures of different phases. α-NaYF4:Yb,Er@α-NaYF4, α-NaYF4:Yb,Er@β-NaYF4, β-NaYF4:Yb,Er@α-NaYF4, and β-NaYF4:Yb,Er@β-NaYF4 core/shell structures were prepared by adopting the required conditions to achieve the desired phase. Excess sodium was used to grow hexagonal shell over metastable cubic core under controlled conditions of reaction time and temperature to prevent the structural transition of the core. Upconversion emission spectra have also been obtained. UCL integrated intensities demonstrated about 5-fold enhancement for α-shell over α-core as compared to the core alone and 22-fold enhancement with β-shell. On the other hand, α-shell over β-core exhibited 5-fold enhancement and β-shell over β-core exhibited 6-fold enhancement.
研究领域:
材料科学
·
纳米技术
·
光学
✓ 已验证
DOI
PubMed
高影响因子
MACROMOLECULES
·
2025
·
IF 5.2
Mengru Ding,Lingling Ni,Ying Zheng,Bao Wang,Chengtao Yu,Guorong Shan,Yongzhong Bao,Junfeng Liu,Pengju Pan
Long-spaced aliphatic polyesters are typical sustainable polyethylene (PE)-like polymers. However, the presence of a low amount of ester groups can exert a profound effect on the crystalline structure of such PE-like polymers. Herein, we synthesized a series of long-spaced aliphatic polyesters bearing two proximate ester groups from ethylene glycol (EG) and n-methylene diacids (n = 9–18) and investigated their polymorphic crystallization and phase transitions. We find that the EG-based polyesters exhibit unique crystal polymorphism and phase transition behaviors. They can form a metastable hexagonal phase (form II) with nontilted, extended chain conformations at low temperatures or during rapid cooling but adopt the thermally stable orthorhombic phase (form I) with tilted chain packing at high temperatures or under slow cooling. Form I demonstrates a more densely packed chain structure and displays distinct mechanical properties compared to form II. The metastable hexagonal phase can transform into an orthorhombic phase during heating through a melt-recrystallization mechanism. This study advances the current understanding of the multiphase crystallization of PE-like long-spaced polyesters.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2024
·
IF 8.3
Yu Yan,Weiliang Peng,Bin Yuan,Shaobo Li,Jinxia Liang,Qiying Han,Sen Li,Renzong Hu
It is essential and still remains a big challenge to obtain fast-charge anodes with large capacities and long lifespans for Li-ion batteries (LIBs). Among all of the alternative materials, molybdenum trioxide shows the advantages of large theoretical specific capacity, distinct tunnel framework, and low cost. However, there are also some key shortcomings, such as fast capacity decaying due to structural instability during Li insertion and poor rate performance due to low intrinsic electron conductivity and ion diffusion capability, dying to be overcome. A unique strategy is proposed to prepare Ti-h-MoO3–x@TiO2 nanosheets by a one-step hydrothermal approach with NiTi alloy as a control reagent. The density functional theory (DFT) calculations indicate that the doping of Ti element can make the hexagonal h-MoO3–x material show the best electronic structure and it is favor to be synthesized. Furthermore, the hexagonal Ti-h-MoO3–x material has better lithium storage capacity and lithium diffusion capacity than the orthogonal α-MoO3 material, and its theoretical capacity is more than 50% higher than that of the orthogonal α-MoO3 material. Additionally, it is found that Ti-h-MoO3–x@TiO2 as an anode displays extremely high reversible discharge/charge capacities of 1326.8/1321.3 mAh g–1 at 1 A g–1 for 800 cycles and 611.2/606.6 mAh g–1 at 5 A g–1 for 2000 cycles. Thus, Ti-h-MoO3-x@TiO2 can be considered a high-power-density and high-energy-density anode material with excellent stability for LIBs.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
PubMed
高影响因子
Journal of Materials Chemistry C
·
2016
·Vol. 4
·期 26
·6327-6335
·
IF 5.066
Weijing Yao,Qingyong Tian,Jun Liu,Zhaohui Wu,Shuyuan Cui,Jin Ding,Zhigao Dai,Wei Wu
Up-conversion materials can be applied in anti-counterfeit fields because of their high concealment and high up-conversion fluorescence efficiency. Herein, different lanthanide ions-doped β-NaYF4 up-conversion micro-particles (UCMPs) with uniform hexagonal morphology were synthesized on a large-scale (more than 0.5 g) via a facile hydrothermal method. It is very interesting to find out the fluorescence intensity and the eventual morphology of the UCMPs were highly dependent on the reaction conditions. Then, the optimal UCMPs with uniform morphology and strong fluorescence intensity were selected as promising candidates for preparing ink. Eventually, we successfully printed designable and multicolor fluorescent patterns on flexible substrates (common paper and polyethylene terephthalate, PET) using the as-prepared β-NaYF4:Yb3+,Tm3+/Er3+/Eu3+ UCMPs inks. Under ambient conditions, the printed patterns on conventional paper are invisible, while such printed patterns on PET are white. However, all the patterns could display blue, yellow-green and green fluorescence patterns under the irradiation of a 980 nm laser when using the β-NaYF4:Yb3+,Tm3+/Er3+/Eu3+ UCMPs inks. We envision that the UCMPs fluorescent inks-based flexible and rapid screen printing patterns have enormous potential for anti-counterfeit and security applications.
研究领域:
材料科学
·
光学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
ChemPhotoChem
·
2017
·Vol. 1
·期 8
·369-375
·
IF 0
Xuesong Zhai,Ying Wang,Xiaojuan Liu,Shihu Liu,Pengpeng Lei,Shuang Yao,Shuyan Song,Liang Zhou,Jing Feng,Hongjie Zhang
Graphical It′s all under control : Ultrasmall NaYF 4 :Yb,Er upconversion nanocrystals have been prepared by the simultaneous addition of two methanolic solutions of NH 4 F and NaOH into a rare-earth-salt precursor solution. A large number of hexagonal-phase seeds are quickly formed as a result of the low energy barrier, resulting in an ultrasmall particle size. Precise control over the size and crystallographic phase of nanocrystals allows the manipulation of their properties and applications as desired. Hexagonal-phase NaYF 4 (β-NaYF 4 ) upconversion nanocrystals with efficient luminescence are quite desirable for bio-applications, but synthetic control over the nanocrystallite size remains challenging. Herein we verify experimentally that control of the hexagonal-phase nucleation is crucial for controlling the final particle size and the number of hexagonal-phase seeds strongly depends on the actual F(Na):Y ratio. A negligible number of hexagonal-phase seeds were formed at low ratio whereas the high ratio yields a very large number of seeds. We also identify that the actual F(Na):Y ratio is more likely related to the different methods employed for the addition of NH 4 F and NaOH rather than its initial feeding ratio. By taking advantage of this dependence and varying the reaction conditions (temperature and time), β-NaYF 4 :Yb,Er nanocrystals with a size smaller than 6 nm can be synthesized. Theoretical modeling shows a good agreement with the experimental results.
研究领域:
材料科学
·
纳米技术
·
化学工程
✓ 已验证
产品关联
DOI
OPTIK
·
2020
·
IF 2.187
Xuelong Liu,Long Yan,Songbin Liu,Qiqing Li,Bo Zhou
Lanthanide-doped upconversion nanomaterials in particular the ultrasmall (<10 nm) nanoparticles have recently gained substantial attention owing to their bright potential in diverse frontier applications such as multicolor displays and biomedical applications. However, it is still lack of mechanistic researches on crystal growth and a fine-tuning of luminescent properties for the ultrasmall nanoparticles. Herein, we report the controllable synthesis of ultrasmall hexagonal core-shell nanoparticles through controlling the crystal growth kinetics processes. By precise manipulation of the reaction temperature and lanthanide ions doping, the size of utrasmall nanoparticles can be reduced to 2.51 nm still with the hexagonal phase, which is critically important for upconversion. Besides, an epitaxial growth of a NaGdF 4 inert-shell layer outside the core nanoparticles leads to a 23.5 times enhancement of the upconversion emission still with the ultrasmall size (6.21 nm). Moreover, the RGB primary color emissions are achieved through properly lanthanide ions doping in these ultrasmall nanoparticles and a set of multicolor output covering the visible spectral range are further obtained by precisely adjusting the mix ratio of the RGB ultrasmall nanoparticles, which shows a great potential in full-color displays and anti-counterfeiting applications.
研究领域:
材料科学
·
光学
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
SENSORS AND ACTUATORS B-CHEMICAL
·
2025
·
IF 7.7
Ping Yu,Lin Wang,Huan Liu,Anfeng Yu,Xinmei Liu,Zhe Yang
Developing reliable and cost-effective optical hydrogen sensors detecting hydrogen leakage at room temperature is of paramount importance. It requires that hydrogen sensors show a rapid and significant color change in low concentration H 2 /air mixtures, which remains challenging. Herein, we demonstrate an eye-readable hydrogen sensor based on Pt decorated hexagonal WO 3 (W 0 /300/Pt). It is evidenced W 0 /300/Pt exhibits excellent gasochromic properties, with reflectivity differences of 78% and 73% and fast coloring times of 3.10 s and 2.64 s in 10% H₂/Ar and 10% H₂/air. Moreover, W 0 /300/Pt shows an obvious color change from light gray to dark blue finally with ΔE value of 71, and exhibits a detect limitation less than 0.1% H 2 in 1 s. The gasochromic mechanism related to crystalline phase structure was unveiled via in situ characterization techniques. This study also presents novel evidence that bolsters the “localized water molecules” model and provides theoretical insights for the advancement of highly sensitive WO 3 gasochromic materials.
研究领域:
材料科学
·
化学
✓ 已验证
DOI
高影响因子
Communications Chemistry
·
2021
·Vol. 4
·期 1
·1-12
·
IF 6.581
Ge Xuan,Hu Qiaodan,Yang Fan,Xu Jun,Han Yanfeng,Lai Pingsheng,Qin Jingyu,Li Jianguo
The crystallization processes of titanates are central to the fabrication of optical and electrical crystals and glasses, but their rich polymorphism is not fully understood. Here, we show when and how polymorphic selection occurs during the crystallization of barium titanate (BaTiO 3 , BT) using in situ high energy synchrotron X-ray diffraction and ab initio molecular dynamic simulation. An anomalous structure transition is found in molten BT during cooling across the cubic-hexagonal transition temperature, which enables nucleation selection of BT by manipulating the undercooling: a cubic phase is preferred if nucleation is triggered at large undercooling, whereas a hexagonal phase is promoted at small undercooling. We further reveal that the nucleation selection between the cubic and the hexagonal phase is regulated by the intrinsic structure property of the melt, in particular, the degree of polymerization between Ti-O polyhedra. These findings provide an innovative perspective to link the polymorphic crystallization to the non-isomorphic structure transition of the melt beyond the conventional cognition of structural heredity.
研究领域:
材料科学
·
凝聚态物理
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）