CHINESE JOURNAL OF CATALYSIS
·
2022
·Vol. 43
·期 9
·2443-2452
·
IF 12.92
Yaojia Cheng,Haoqiang Song,Jingkun Yu,Jiangwei Chang,Geoffrey I.N. Waterhouse,Zhiyong Tang,Bai Yang,Siyu Lu
The sluggish kinetics of oxygen reduction reaction (ORR) hinders the commercialization of Zn-air batteries (ZABs). Manipulating the electronic structure of electrocatalysts to optimize the adsorption energy of oxygen-containing intermediates during the 4e − ORR offers a practical route toward improving ORR kinetics. Herein, we designed a novel ORR electrocatalyst containing Co single atoms and nanoparticles supported by carbon dots-derived carbon nanoflowers (Co SAs/NPs CNF). Co SAs/NPs CNF possessed a very high ORR activity ( E 1/2 of the Co SAs/NPs CNF catalyst is 0.83 V ( vs. RHE)), and outstanding catalytic performance and stability when used as the air-electrode catalyst in rechargeable ZABs (152.32 mW cm −2 , 1000.58 mWh g Zn −1 , and over 1300 cycles at a current density of 5 mA cm −2 ). The Co SAs and Co NPs cooperated to improve electron and proton transfer processes during ORR. Theoretical calculations revealed that the presence of adjacent Co NPs optimized the electronic structure of the isolated Co-N 4 sites, significantly lowering the energy barriers for the rate-determining step in ORR (adsorption of *OOH) and thereby delivering outstanding ORR performance. This work reveals that the combination of supported single-atom sites and metal nanoparticles can be highly beneficial for ORR electrocatalysis , outperforming catalysts containing only Co SAs or Co NPs.
研究领域:
电化学
·
纳米材料科学
·
能源化学
·
催化化学
·
先进电池技术
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CHEMISTRY
·
2013
·Vol. 31
·期 3
·371-376
·
IF 0.917
Wei Zhu,Haoyang Wang,Haihui Peng,Guosheng Liu,Yinlong Guo
Pd-catalyzed oxidative coupling reaction was of great importance in the aromatic C H activation and the formation of new C O and C C bonds. Sanford has pioneered practical, directed C H activation reactions employing Pd(OAc) 2 as catalyst since 2004. However, until now, the speculated reactive Pd(IV) transient intermediates in these reactions have not been isolated or directly detected from reaction solution. Electrospray ionization tandem mass spectrometry (ESI-MS/MS) was used to intercept and characterize the reactive Pd(IV) transient intermediates in the solutions of Pd(OAc) 2 -catalyzed oxidative coupling reactions. In this study, the Pd(IV) transient intermediates were detected from the solution of Pd(OAc) 2 -catalyzed oxidative coupling reactions by ESI-MS and the MS/MS of the intercepted Pd(IV) transient intermediate in reaction system was the same with the synthesized authentic Pd(IV) complex. Our ESI-MS(/MS) studies confirmed the presence of Pd(IV) reaction transient intermediates. Most interestingly, the MS/MS of Pd(IV) transient intermediates showed the reductive elimination reactivity to Pd(II) complexes with new C O bond formation into product in gas phase, which was consistent with the proposed reactivity of the Pd(IV) transient intermediates in solution.
研究领域:
有机化学
·
金属有机化学
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分析化学
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催化化学
·
质谱学
✓ 已验证
DOI
高影响因子
Journal of Energy Chemistry
·
2020
·
IF 7.216
Xiaojing Jiang,Jianian Chen,Fenglei Lyu,Chen Cheng,Qixuan Zhong,Xuchun Wang,Ayaz Mahsud,Liang Zhang,Qiao Zhang
Controllable fabrication of Fe-N-C based single-atom catalysts (SACs) for enhanced electrocatalytic performance is highly desirable but still challenging. Here, an in situ surface-confined strategy was demonstrated for the synthesis of single atomic Fe-N 4 on N-doped carbon nanoleaves (L-FeNC). The in situ generated Zn 3 [Fe(CN) 6 ] 2 could not only serve as a protection layer against collapse of nanoleaves but also provide abundant Fe source for the formation of Fe-N moieties during pyrolysis, leading to high surface area and high graphitization degree of L-FeNC simultaneously. Benefiting from abundant Fe-N 4 active sites, enhanced mass and charge transfer, the as-prepared L-FeNC manifested a half-wave potential of 0.89 V for oxygen reduction reaction (ORR) in 0.1 M KOH. A maximum power density of 140 mW cm −2 and stable discharge voltage even after operation for 50,000 s have been demonstrated when the L-FeNC was used as air cathode for Zn-air battery. This work not only provided a unique surface-confined strategy for the synthesis of two-dimensional nanocarbons, but also demonstrated the significant benefit from rational design and engineering of Fe-N-C SACs, thus offering great opportunities for fabrication of efficient energy conversion and storage devices.
研究领域:
材料科学
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电化学
·
能源存储与转换
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纳米科技
·
催化化学
✓ 已验证
DOI
高影响因子
POLYMERS FOR ADVANCED TECHNOLOGIES
·
2017
·Vol. 28
·期 11
·1438-1447
·
IF 1.907
Xin Liu,Xuewen Guo,Yunfei Zhi,Shaoyun Shan,Yonghao Ni,Qingming Jia
The recent development of sulfur dioxide (SO 2 ) polymerization has seen a renaissance in its chemistry, especially poly(olefin sulfone)s from the copolymerization of SO 2 , and unsaturated hydrocarbons can be found to have many applications, including transient electronic packaging, drug delivery, and electron beam-resistant materials. In this work, a type of functional poly(norbornene sulfone) was synthesized via two different polymerization methods. Aiming to understanding the effects of different polymerization methods on poly(olefin sulfone)s and gain further understanding on the kinetics of poly(olefin sulfone)s's thermal instability, we investigated their detailed thermal degradation behaviors using thermogravimetry and analyzed the resultant kinetics in accordance with three kinetic models. The results supported the conclusion that although the poly(norbornene sulfone)s obtained have different activation energy, the thermal degradation kinetics are the same and also obey the D n type. Copyright © 2017 John Wiley & Sons, Ltd.
研究领域:
高分子化学
·
材料科学
·
热分析
·
功能高分子
·
可控降解材料
✓ 已验证
DOI
高影响因子
TETRAHEDRON
·
2014
·Vol. 70
·期 47
·9033-9040
·
IF 2.817
Tao Liu,Meng-Meng Liu,Xiao-Wen Zheng,Chong-Yang Du,Xiang-Yang Cui,Lu Wang,Ling-Li Han,Zhang-Yu Yu
The redox reactions of p -hydroquinone and pyrocatechol undergo a two-proton-two-electron process in aqueous solution. We calculated their redox potentials at the B3LYP/6-311+G(d,p) level, and verified the values by employing cyclic voltammetry experiments. Then we selected seven substituent groups (–F, –Cl, –OH, –COOH, –CN, –NH 2 , and –NO 2 groups) to systematically investigate the substituent effect , including the sort, position, and number of the substituent, on the redox potentials of p -hydroquinone and pyrocatechol. The calculated results show that –NH 2 and –OH groups can decrease the redox potentials, while –F, –Cl, –COOH, –CN, and –NO 2 groups increase the potential values of p -hydroquinone and pyrocatechol. The calculations can accurately predict the substituent effects on the redox potentials of pyrocatechol and p -hydroquinone. We would expect that the accurate calculation results for the model systems could be applied in the prediction of electrode potentials of other molecules.
研究领域:
物理有机化学
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电化学
·
计算化学
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分子设计
·
生物电化学
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2018
·
IF 3.779
Nan Liu,Zhi Dong,Zongqing Ma,Liming Yu,Chong Li,Chenxi Liu,Qianying Guo,Yongchang Liu
The bimodal distribution of tungsten grain size, which is also called bimodal structure, is a universal phenomenon in synthesizing tungsten based nanopowders by wet chemical method , and could significantly deteriorate further sintering characteristics of the powders. In this paper, W-Y 2 O 3 composite nanopowders with small grain size and no bimodal structure were synthesized by an improved wet chemical method. It was found that reaction conditions, especially the hydrogen ion concentration(ρ(H + )) could significantly influence the microstructure and morphology of the prepared composite nanopowders and has an optimum value of approximately 0.16 mol L −1 . W-Y 2 O 3 composite nanopowders synthesized under this optimum value got not only the minimum average grain size, which is about 17 nm, but also the best grain size uniformity with no bimodal structure. The microstructure of co-deposited precursors and prepared powders was analyzed in detail to figure out the specific influence mechanism of ρ(H + ), and it was indicated that ρ(H + ) could influence the microstructure and the Y 2 O 3 content of the reduced powders through affecting the fraction of precursor that has little yttrium content, which may lead to the bimodal distribution of tungsten grain size of the prepared powders. Furthermore, the formation mechanism of bimodal structure was systematically analyzed and a feasible method was proposed to eliminate the bimodal structure. It is suggested that the bimodal distribution of tungsten grain size is attributed to the distribution of Y 2 O 3 during hydrogen reduction process and can be well avoided by controlling ρ(H + ).
研究领域:
材料科学
·
纳米材料
·
粉末冶金
·
无机非金属材料
·
功能材料
✓ 已验证
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2019
·
IF 3.131
Xiaotong Sun,Luting Yan,Runxiang Xu,Mingyuan Xu,Yanyun Zhu
TiO 2 presents a broad application prospect in the field of degradation of environmental pollutants. However, the development of TiO 2 photocatalyst has been limited by two factors, namely, narrow spectral response range and low quantum efficiency . Surface coating can selectively change the physical and chemical properties of core particles, whereas the synergistic action between core and shell can optimize material performance. In this paper, surface modification of titanium dioxide (TiO 2 ) by dopamine polymerization was used to improve its photocatalytic performance. Among polydopamine (PDA)-modified TiO 2 , TiO 2 @PDA-0.4 mg/mL-2 h showed the best degradation rate of Rhodamine B (RhB): the degradation rate reached 99.28% and 77.40% after 1.5 h of ultraviolet–visible (UV–vis) and visible (Vis) light irradiation, respectively. Compared with the uncoated TiO 2 , the degradation rate has shown improvement, especially under Vis light irradiation, with the photocatalytic performance improving by 35.04%. Absorption, emission, and impedance spectra showed that surface modification of TiO 2 with suitable thickness of PDA effectively increased light absorption and promoted separation of photogenerated carriers . High-performance liquid chromatography–mass spectrometry revealed the differences in photocatalytic degradation mechanism of TiO 2 @PDA to RhB under UV–vis and Vis light irradiation. Compared with those under UV–vis light irradiation, the intermediate products under Vis light irradiation are relatively simple. TiO 2 @PDA generated more electrons, which interacted with H 2 O to produce large amounts of ·OH and holes under UV–vis light irradiation in comparison with that under Vis light irradiation. In addition to deacetylation , deamination , and decarboxylation by hydroxylation , excess ·OH in the photocatalytic process would attack benzene rings directly to produce N , N -diethylacetamide.
研究领域:
材料科学
·
环境化学
·
光催化
·
纳米材料
·
表面工程
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS CHEMISTRY
·
2011
·Vol. 21
·期 40
·16028-16034
·
IF 5.101
Jun Shi,Zhengzheng Zhang,Gefei Li,Shaokui Cao
Alginate/CaCO3 hybrid beads with pH- and thermal-responsive drug release properties were prepared under compressed CO2 using aliphatic poly(urethane-amine)s (PU) as the thermal-responsive component. Polyacrylic acid (PAA) was used as a crystal growth additive to control the structure of the hybrid beads. The hybrid beads were characterized by using scanning electron microscopy, X-ray powder diffraction and thermogravimetric analysis. The interaction between PAA and aliphatic PU contributed to the formation of alginate beads with a compact CaCO3 shell. Indomethacin release behaviour was found to be pH- and thermal-responsive. The release profiles were sustained with CaCO3 microparticles, indicating that the compact CaCO3 shell could hinder the permeability of the encapsulated drug and reduce the drug release effectively. The results suggest that the hybrid alginate beads can be used as “smart” polysaccharide materials for sustained dual-responsive drug delivery.
研究领域:
生物材料
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药物递送系统
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高分子科学
·
纳米医学
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药剂学
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生物化学
·
组织工程
✓ 已验证
DOI
高影响因子
ELECTROCHIMICA ACTA
·
2022
·
IF 7.336
Feihong Zhang,Qiaohang Weng,Yanxiang Zhang,Na Ai,San Ping Jiang,Chengzhi Guan,Yanqun Shao,Huihuang Fang,Yu Luo,Kongfa Chen
Solid oxide fuel cells (SOFCs) are the most efficient energy conversion technology to convert the chemical energy of fuels like hydrogen, natural gas, etc. to electricity. However, one of the limiting factors in the commercial viability of SOFCs technologies is the time-consuming and high-cost multiple cell fabrication processes. Here, we report the development of a facile procedure for the preparation of an electrolyte-supported cell with a Ni-Gd 0.1 Ce 0.9 O 1.95 composite anode and a La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ cathode, and the fabrication procedure of the electrodes decreases from four steps of screen-printing and sintering of conventional cell preparation processes to two steps of screen-printing using a direct assembly approach without the high-temperature sintering steps. The most important observation is the simultaneous formation of the electrode/electrolyte interfaces of both the anode and cathode by in situ passing a current through the directly assembled cells at 800 ℃. The power density of the directly assembled cell reaches 0.41 W cm −2 at a voltage of 0.7 V and 800 ℃, close to 0.46 W cm −2 of the sintered cell. The directly assembled cell shows comparable operational stability to the sintered cell at 800 ℃ for 100 h. This work sheds light on the facile fabrication of electrolyte-supported cells with substantially simplified preparation procedures and reduced costs.
研究领域:
材料科学
·
能源化学
·
电化学
·
燃料电池技术
·
无机功能材料
✓ 已验证
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2017
·
IF 3.387
Lichun Ma,Nan Li,Guangshun Wu,Guojun Song,Xiaoru Li,Ping Han,Gang Wang,Yudong Huang
A novel amine-based functionalization method was developed to improve the interfacial adhesion between TiO 2 NWs and CFs in supercritical water. The microstructure, morphology and mechanical properties of CFs were investigated. It was found that introducing hexamethylenetetramine (HMTA) dendrimers and branched polyethyleneimine (PEI) on CF could increase significantly the adhesion strength between CF and TiO 2 NWs and their interfacial shear strength with epoxy resin, and the order is CF-PEI-TiO 2 NWs > CF-HMTA-TiO 2 NWs > CF-COOH-TiO 2 NWs > CF-TiO 2 NW. Meanwhile, the reinforcing mechanisms and interfacial failure modes have also been discussed. We believe that these effective methods may provide theoretical foundation for the preparation of high performance composite materials.
研究领域:
材料科学
·
复合材料界面工程
·
纳米材料修饰
·
高分子基复合材料
✓ 已验证
DOI
高影响因子
CHINESE CHEMICAL LETTERS
·
2016
·Vol. 28
·期 1
·49-54
·
IF 1.947
Qi-Feng Li,Chao Wang,Xiao-Zheng Lan
Latent heat storage performance of a layered perovskite-type compound, 1-C 14 H 29 NH 3 ) 2 ZnCl 4 (C 14 Zn), embedded in a series of silica gel (SG) with pore sizes of d = 15–200 nm is investigated using differential scanning calorimetry (DSC), and powder X-ray diffractions (XRD). C 14 Zn in the nanopores of silica gel shows size-dependent phase transition temperature, enthalpy change and supercooling. They have a stable transition temperature and heat capacity at each size in a short-term thermal cycling. Similar X-ray diffraction patterns are observed for the nano-sized and the bulk C 14 Zn. The encapsulation of a phase change material in nanopores is a new way of tuning its thermal energy storage properties for a wider range of temperature regulation.
研究领域:
材料科学
·
热力学
·
纳米科技
·
能源存储
·
功能材料
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING RESEARCH & DESIGN
·
2018
·
IF 2.795
Maogang He,Siqi Liu,Lihang Bai,Xiangyang Liu
Magnetic ionic liquids (MILs), combines the general properties of ionic liquid with magnetic properties, are starting to attract interest in the field of propane/propylene separation and CO 2 capture. Solubility data of propane, propylene, cyclopropane and CO 2 in magnetic ionic liquid 1-butyl-3-methylimidazolium tetrachloroferrate [bmim][FeCl 4 ] at temperatures of (303, 313, 323, 333, 343) K and pressures up to 3300 kPa were determined in the present work. The relative expanded uncertainty of solubility measurement is estimated to be less than 4% with a level of confidence of 95%. The Henry’s constants for the four gases in [bmim][FeCl 4 ] and selectivity of C 3 H 6 /C 3 H 8 in [bmim][FeCl 4 ] were calculated. And the thermodynamic properties of solvation concerned about the Gibbs energy (Δ sol G ∞ ), the enthalpy (Δ sol H ∞ ) and the entropy (Δ sol S ∞ ) of solvation were also obtained to offer knowledge for understanding the progress of gases dissolved in [bmim][FeCl 4 ]. The experimental results were correlated with a modified KK equation and NRTL equation.
研究领域:
化学工程
·
分离科学
·
物理化学
·
环境化工
·
绿色溶剂技术
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）