ELECTROCHIMICA ACTA
·
2022
·
IF 7.336
Shuwen Zhao,Yifan Zhao,Ji Chen,Ruijie Dai,Weijie Zhou,Jinpeng Yang,Xuan Zhao,Zhengang Chen,Yao Zhou,Hua Zhang,Anran Chen
To solve the problem of low hydrogen production efficiency from water electrolysis, increasing research is focusing on improving the efficiency of the complex oxygen evolution reaction (OER) that occurs at the anode. The preparation of high-efficiency OER electrocatalysts is key to improving the OER efficiency and the only way forward. In this work, a NiFeCo ternary OER high-efficiency electrocatalyst, NiFeCoP@CAP/NF, comprising coexisting crystalline and amorphous phases (CAP), was prepared on nickel foam (NF) by a simple one-step hydrothermal reaction and high-temperature gas-phase phosphating. The as-synthesized catalyst exhibits an ultralow overpotential of 202 mV (10 mA cm −2 ) in 1 M KOH solution with a Tafel slope (η10 = 202 mV) of 28.9 mV dec −1 . Further, it is understood that owing to the combination of the crystalline and amorphous phases, the catalyst can rapidly transform the amorphous phase into the true active (NiOOH) phase of the OER process while retaining the fast charge transport properties of the crystalline phase, as observed by in situ Raman analysis.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
MACROMOLECULES
·
2025
·
IF 5.2
Ziyuan Zhou,Binghua Wang,Changyu Shen,Bin Zhang
Previous research studies on isotactic polypropylene (iPP) have shown that the ratio of growth rate β to α phase (Gβ/Gα) exceeds 1 when the crystallization temperature (Tc) is between the lower and upper critical temperature limits (Tc** ∼ 100 °C and Tc* ∼ 141 °C, respectively), due to the faster surface kinetics of β-iPP. However, in this work, we observed that when the film thickness (d) decreases from 24 to 9 nm, the temperature interval of Gβ/Gα > 1 narrows and even disappears, as Tc* gradually shifts to lower temperatures while Tc** remains constant. This is presumably because, as d decreases, the width (wd) of the depletion zone of β-iPP expands more significantly than that of α-iPP, resulting in slower diffusion toward the growth front of β-iPP. Consequently, Gβ decreases more than Gα as d diminishes, leading to a reduction in the value of Gβ/Gα, especially at higher Tc, where Gβ/Gα becomes less than 1. Moreover, we found that the diffusion activation energy (Eaβ) of β-iPP is consistently greater than that of α-iPP (Eaα) at a given d, and the gap between Eaα and Eaβ increases as d decreases. This further highlights that the slower diffusion process for β-iPP progressively becomes the main factor affecting the difference between Gα and Gβ as d diminishes.
研究领域:
材料科学
·
高分子物理
✓ 已验证
DOI
高影响因子
CHEMISTRY-A EUROPEAN JOURNAL
·
2015
·Vol. 21
·期 9
·3671-3681
·
IF 5.731
Bin Wu,Keyang Chen,Yuchen Deng,Jian Chen,Chengjie Liu,Rongshi Cheng,Dongzhong Chen
Graphical Metalloporphyrin liquid crystals : Well-organized hexagonal columnar mesophases of broad temperature ranges have been achieved in metal complexes of easily available fatty acid octaester substituted porphyrins. The liquid crystallinity of the free base and the metal porphyrins can be tuned with variant length side-chain substituents and different coordinated metal ions (see figure; TPP=tetraphenyl porphyrin). A series of meta -substituted fatty acid octaester derivatives and their transition-metal complexes of meso - tetraphenyl porphyrins (TPP-8OOCR, with R=C n −1 H 2 n −1 , n =8, 12, or 16) have been prepared through very simple synthesis protocols. The thermotropic phase behavior and the liquid crystalline (LC) organization structures of the synthesized porphyrin derivatives were systematically investigated by a combination of differential scanning calorimetry (DSC), polarized optical microscopy (POM), and variable-temperature small-angle X-ray scattering/wide-angle X-ray scattering (SAXS/WAXS) techniques. The shorter octanoic acid ester substituted porphyrin (C8-TPP) did not show liquid crystallinity and its metal porphyrins exhibited an uncommon columnar mesophase. The lauric acid octaester (C12-TPP) and the palmitic acid octaester (C16-TPP) series porphyrins generated hexagonal columnar mesophase Col h . Moreover, the metal porphyrins C12-TPPM and C16-TPPM with M=Zn, Cu, or Ni, exhibited well-organized Col h mesophases of broad LC temperature ranges increasing in the order of TPPNi
研究领域:
材料化学
·
有机化学
·
生物仿生材料
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2013
·
IF 1.304
Fuhai YU,Junhu WANG,Kunfeng ZHAO,Jie YIN,Changzi JIN,Xin LIU
A series of novel TiO 2 nanocomposite crystals with superior visible-light-driven photocatalytic activity were successfully prepared using a soft chemical solution process involving direct reaction of aqueous H 2 O 2 with a 2-ethoxyethanol solution of tetraisopropyl titanate before calcination of the resulting peroxo-titanium complexes at 500 °C for 4 h. The synthesized TiO 2 samples are composed of anatase and rutile phases , and the ratio of rutile could be continuously tuned from 0 to 96% by altering the 2-ethoxyethanol volume. There are clear red-shifts in the UV-Vis absorption spectra and apparent band gap narrowing for the synthesized TiO 2 in comparison with Evonik P-25. The synthesized TiO 2 samples are found to be much more efficient for methylene blue degradation under visible-light irradiation. The optimized sample (2-ethoxyethanol: 5 ml; rutile in bulk: 46%) exhibits 5-fold higher adsorption capacity and 3-fold higher photocatalytic activity than those of Evonik P-25 (λ ≥ 400 nm). Characterizations including X-ray diffraction and Raman spectroscopy reveal that the surface of the optimized TiO 2 sample only contains a small quantity of rutile. It is concluded that the surface phase composition and distribution of the TiO 2 nanocomposite crystals are essential to their greatly enhanced photocatalytic activities and strong adsorption capacities. In addition, the concentration of defects existing in the synthesized TiO 2 is also regarded to account for these enhanced properties. 摘要 采用新的化学溶液法, 通过不同体积的钛酸四异丙酯的2-乙二醇单乙醚溶液与一定浓度的H 2 O 2 水溶液直接反应并对生成的钛过氧化配合物进行焙烧, 制备了一系列TiO 2 光催化剂. 表征发现, 所得TiO 2 样品为金红石和锐钛矿的纳米复合晶体, 改变2-乙二醇单乙醚的体积可实现金红石相比例在0–96%广范围的调变.与商业二氧化钛P-25相比, 所得的TiO 2 紫外-可见光吸收谱出现明显红移, 间隙能降低, 在可见光照射下, 该样品对亚甲基蓝有良好的降解活性. 当2-乙二醇单乙醚的添加量为5 ml时, 所得样品体相中金红石相比例接近50%, 其光催化活性和吸附性能最好, 可分别是P-25的3倍和5倍. 拉曼光谱结合X射线衍射等表征结果表明, 该样品的表面仅含少量的金红石相. TiO 2 纳米复合晶表面晶相的组成和分布对其光催化降解亚甲基蓝的活性及其吸附能力有直接的影响. 另外, TiO 2 纳米复合晶的缺陷浓度也是增强其光吸收能力, 提高其可见光光催化活性的原因之一.
研究领域:
材料化学
·
光催化
·
纳米材料
·
环境科学
·
表面科学
·
无机化学
✓ 已验证
DOI
高影响因子
DYES AND PIGMENTS
·
2017
·
IF 3.473
Yunjian Wang,Wanying Wu,Xianliang Fu,Mingzhu Liu,Jing Cao,Congying Shao,Shifu Chen
This work explores the phase transition and its impact on photoluminescent properties of metastable scheelite-type, with and without Eu 3+ doped, CdWO 4 nanophosphors. A series of scheelite structure CdWO 4 :xEu 3+ (x = 0, 0.025, 0.05, 0.075, 0.10) samples were synthesized using a simple solvothermal method. The X-ray diffraction results indicate that the prepared samples were single phase in a tetragonal scheelite-type structure, and completely transformed into pure monoclinic wolframite structure after sintering at 450 °C for 2 h. It was revealed by Rietveld analysis that Eu 3+ doping induced a lattice contraction of both scheelite and wolframite CdWO 4 structures. The impact of Eu 3+ doping on the crystal structure and the band structure were further probed by FT-IR, Raman and UV–Vis spectroscopy. SEM images show that the morphology of the prepared samples also changed in the phase transition and the Eu 3+ doping processes. All samples showed a broad multi-color luminescence emission in the range from 400 to 640 nm under 280 nm excitation. The relative intensities of the blue-green emission originated from CdWO 4 matrix and the red emission ascribed to Eu 3+ can be regulated by both the crystal structure and Eu 3+ doping levels. The energy transfer process between WO 4 groups in scheelite structure CdWO 4 and WO 6 groups in wolframite structure CdWO 4 and Eu 3+ was discussed in detail based on the photoluminescent excitation and emission spectra. The synthetic approach reported here allows the control over CdWO 4 polymorphs and this kind of luminescent material has wide applications in white-LED, chemosensors and bioimaging .
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
Materials Research Express
·
2025
·
IF 2.2
Ziyi Liu,Juanjuan Xing,Shuanglong Yuan,Hua Tong
Barium titanate (BaTiO₃) nanoparticles were synthesized via a hydrothermal method using barium hydroxide (Ba(OH)₂) and titanium oxide (TiO₂) as starting materials. The present study investigates the influence of TiO₂ sources on BaTiO3 nanoparticle crystallinity and morphology. A comprehensive statistical analysis was conducted, revealing a direct correlation between the phase and size of the TiO₂ and the properties of the BaTiO₃. Anatase TiO₂, with a size ranging from 5-30 nm, was found to yield uniform spherical BaTiO₃ nanoparticles with sizes ranging from 66.1 ± 9.4 nm to 80.3 ± 10.8 nm. Conversely, rutile TiO₂, with a size of 10 nm, yielded irregular particles with an average size of 386.6 ± 146.99 nm. XRD analysis demonstrated that smaller anatase TiO₂ (5 nm) exhibited a propensity to favor cubic-phase BaTiO₃, while larger anatase TiO₂ (10–30 nm) exhibited a propensity to promote tetragonal-phase dominance. Conversely, rutile-derived BaTiO₃ exhibited a mixed phase (tetragonal-to-cubic ratio: 2:3). Kinetic studies of precursor synthesis have demonstrated that 5 nm anatase TiO₂ facilitates the rapid nucleation of BaTiO₃ within 30 seconds, reaching full conversion. This is in contrast to the slower kinetics caused by larger anatase TiO₂ and the negligible reactivity observed for rutile TiO₂. These findings underscore the critical role of TiO2 phase and size in tailoring BaTiO3 nanoparticles for advanced dielectric applications, enabling precise control over particle size (60–80 nm) and crystallinity through precursor engineering.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Molecular Catalysis
·
2017
·
IF 0
Wenwen Ma,Yan Xu,Kaiwen Ma,Yuhui Luo,Yushuang Liu,Hong Zhang
PW 11 Sn/TiO 2 (PW 11 Sn = (OTA) 3 PW 11 SnO 39 , OTA = octadecyl trimethyl ammonium) nanofibres with tunable rutile/anatase phase have been successfully prepared via combining with electrospinning and hydrothermal method . The crystal phase of TiO 2 was influenced by the loading amount of PW 11 Sn and the desulfurization efficiency was related with the crystal phase of TiO 2 . When the loading amount of PW 11 Sn on TiO 2 nanofibres was 50%, DBT could be completely removed using 0.02 g PW 11 Sn/TiO 2 nanofibres as catalysts and [Bmim]PF 6 as extraction agent at 60 °C within 20 min, when O/S value was 6:1. Furthermore, the influences of different morphologies and preparation methods for catalysts on desulfurization efficiencies were investigated in detail. This catalyst can be recovered easily and reused at least 7 times maintaining the catalytic activity. For different substrates, the efficiencies of sulfur removal decreased as the following orders: DBT > 4,6-DMDBT > BT under the same conditions. Finally, the mechanism of desulfurization was also elucidated.
研究领域:
材料科学
·
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
JOURNAL OF APPLIED POLYMER SCIENCE
·
2020
·Vol. 137
·期 38
·49143
·
IF 2.52
Qian Zhang,Guokang Chen,Kun Wu,Jun Shi,Liyan Liang,Mangeng Lu
A biphenyl type liquid crystal epoxy (LCE) monomer 4,4′-di(2,3-epoxyhexyloxy)biphenyl (LCBP4) containing flexible chain was synthesized and the curing behavior was investigated using 4,4′-diaminodiphenylmethane (DDM) as the curing agent. The effect of curing condition on the formation of the liquid crystalline phase was examined. The cured samples show good mechanical properties and thermal stabilities. Moreover, the relationship between thermal conductivity and structure of liquid crystalline domain was also discussed. The samples show high thermal conductivity up to 0.28–0.31 W/(m*K), which is 1.5 times as high as that of conventional epoxy systems. In addition, thermal conductive filler, Al 2 O 3 , was introduced into LCBP4/DDM to obtain higher thermal conductive composites. When the content of Al 2 O 3 was 80 wt%, the thermal conductivity of the composite reached to 1.86 W/(m*K), while that of diglycidyl ether of bisphenol A (Bis-A) epoxy resin/DDM/Al 2 O 3 was 1.15 W/(m*K). Compared with Bis-A epoxy resin, the formation of liquid crystal domains in the cured LCE resin enhanced the thermal conductivity synergistically with the presence of Al 2 O 3 . Furthermore, the introduction of Al 2 O 3 also slightly increased the thermal stabilities of the cured LCE.
研究领域:
材料科学
·
热力学
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2024
·
IF 4.9
Yu Huang,Xinyang Xu,Guangjian Fan,Xiaoxuan Zhu,Lin Zhu,Xi Chen
The effect of TiO 2 crystal phase on the photocatalytic properties of TiO 2 /g-C 3 N 4 heterojunction photocatalyst under sunlight irradiation was investigated through experiments and theoretical calculations. Results reveal that for TiO 2 /g-C 3 N 4 heterojunction photocatalyst, anatase phase TiO 2 can adjust the band edge positions to ensure the generation of strongly oxidizing radical species (·O 2- and ·OH), and rutile phase TiO 2 can effectively reduce the band gap to more efficiently utilize sunlight. Consequently, the combination of g-C 3 N 4 with P25 TiO 2 composed of both anatase and rutile phases is the most favorable combination for sunlight-driven photocatalyst among the obtained three TiO 2 /g-C 3 N 4 heterojunction photocatalyst. P25 TiO 2 and g-C 3 N 4 form a type-II/type-II heterostructure with stepped heterojunction and concave heterojunction. The P/CN photocatalyst exhibits excellent photocatalytic activity with degradation efficiencies for naphthalene reaching 100% within 120 min of sunlight irradiation, as well as considerable stability. The combination of P25 TiO 2 and g-C 3 N 4 has shown significant potentials in improving the separation and transfer efficiency of photogenerated electron-hole pairs, as well as enhancing the utilization of sunlight in photocatalytic process. This work provides a promising strategy for the preparation of highly active TiO 2 /g-C 3 N 4 heterojunction photocatalyst for the effective treatment of naphthalene from water.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
NANOTECHNOLOGY
·
2024
·Vol. 35
·期 15
·155401
·
IF 2.9
Hongjing Wang,Tongqing Zhou,Shan Xu,Kai Deng,Hongjie Yu,You Xu,Xiaonian Li,Ziqiang Wang,Liang Wang
The development of effective and stable cathode electrocatalysts is highly desired for fuel cells. Controlling the composition and morphology of Pd-based materials can provide a great opportunity to improve their oxygen reduction reaction (ORR) performance. Here, we report the synthesis of hexagonal close-packed (hcp) Pd2B nanosheet assemblies (Pd2B NAs) via the boronation reaction between as-synthesized Pd NAs and N,N-dimethylformamide. The hcp Pd2B NAs with uniform pore distribution can provide sufficient active sites for ORRs. The insertion of B atoms can induce the phase transition from face-centered cubic structure to hcp structure, as the most thermodynamically stable phase in the Pd-B alloy, which is beneficial for enhancing the ORR stability and toxicity resistance. Therefore, the hcp Pd2B NAs exhibit superior mass activity, specific activity and excellent stability for ORR. The present strategy of boron-intercalation-triggered crystalline transition of Pd-based nanomaterials is valuable for the design of metal–nonmetal catalysts with enhanced performance.
研究领域:
材料科学
·
电化学
·
催化科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CELLULOSE
·
2019
·Vol. 26
·期 15
·8351-8365
·
IF 3.917
Jia Wei,Liu Yun
Abstract We systematically compare the different properties of cellulose nanocrystals (CNCs) obtained by oxalic acid and sulfuric acid hydrolysis methods. The variant characteristics of two kinds of CNCs were confirmed by XRD, DLS, Zeta, TGA, and SEM techniques. When CNCs were mixed with PEG, and the chiral nematic tissue of CNCs was retained in the solid film to observe the liquid crystal phase by evaporation-induced self-assembly. The brilliant snowflake-like pattern of CNC film was observed through oxalic acid instead of sulfuric acid. More importantly, carboxylated CNCs prepared by oxalic acid was easily formed a liquid crystal phase by adding cationic solutions into 1.27% CNC solution. The extra properties of CNCs obtained by oxalate dihydrate contribute to its potential application prospects in optical devices and chiral separation. Graphic abstract
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
LANGMUIR
·
2024
·
IF 3.7
Yun-Long Mu,Qing He,Chun-Yan Li,Da Sheng,Song-Hai Wu,Yong Liu,Hai-Tao Ren,Xu Han
Although precise regulation of the crystalline structures of metal oxides is an effective method to improve their antibacterial activities, the corresponding mechanisms involved in this process are still unclear. In this study, three kinds of cuprous oxide (Cu2O) samples with different structures of cubes, octahedra, and rhombic dodecahedra (c-Cu2O, o-Cu2O, and r-Cu2O) have been successfully synthesized and their antibacterial activities are compared. The antibacterial activities follow the order of r-Cu2O > o-Cu2O > c-Cu2O, revealing the significant dependence of the antibacterial activities on the crystalline structures of Cu2O. Quenching experiments, as well as the NBT and DPD experiments indicate that ≡CuII─OO• superoxo and ≡CuII─OOH peroxo, instead of •OH, O2•–, and H2O2, are the primary oxidizing species in the oxidative damage to E. coli. Raman analysis further confirms the presence of both ≡CuII─OO• superoxo and ≡CuII─OOH peroxo on the surface of r-Cu2O. On the other hand, the NCP experiment reveals that Cu+, instead of Cu2+, also contributes to the antibacterial process. This study provides new insight into the antibacterial mechanisms of Cu2O.
研究领域:
材料科学
·
微生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）