查找使用阿拉丁产品的科研文献

Extrusion deposition 3D printed PCL/gel/n-HA composite scaffold for bone regeneration

Chenxin Wang,Jie Liu,Mingyue Lin,Rui Zhang,Yufan Li,Yubao Li,Qin Zou

Mesoporosity and Acidity Manipulation in ZSM-23 and their n-Hexadecane Hydroisomerization Performance

Di Bai,Jipeng Meng,Chuang Li,Mingming Zhang,Changhai Liang

Graphical Alkali treatment and acid treatment were conducted on ZSM-23 zeolite, which achieved the acidity manipulation and improved the mesoporosity of the zeolite. The modification of the support was conducive to catalysts when used for n -hexadecane hydroisomerization, which enhanced the selectivity of isomers significantly and inhibited the cracking processes. The enhanced mesoporosity in the networks is expected to offer a potential route to surmount mass-transport constraints within one-dimensional microporous structural zeolites. Highly crystalized ZSM-23 zeolite was synthesized and subsequently post-treated with alkali-etching and acid-etching, the effects of post-treatments on the physical and chemical properties of the parent zeolite were investigated via XRD, N 2 physical adsorption, FE-SEM, TEM, 27 Al MAS NMR, Py-IR and NH 3 -TPD. The catalytic activity of various Pt supported bifunctional catalysts was investigated via n -hexadecane hydroisomerization. The post-treated process not only increased the pore volume as well as the specific surface area, which efficiently improved the diffusion efficiency, but also changed the acidity and acid distribution of zeolite: alkali treatment could increase the content of total Brönsted acid while acid treatment exhibited an opposite trend. Acid treatment effectively promoted the density of weak Brönsted acid sites and suppressed the med-strong Brönsted acid sites. With the manipulation of acidity and development of mesoporosity in zeolite, the formation of isomers and the suppression of cracked products in the n -hexadecane hydroisomerization were accomplished. The catalytic performance of catalysts showed that acid treatment could effectually promote the formation of isomeric products and inhibit cracking reactions. Especially, Pt/Z(1.0 HN) catalyst with suitable distribution of acid sites and textural properties, exhibited an outstanding n -C 16 hydroisomerization performance with the highest i -C 16 yield of 64 wt.% at 340 °C.

Soot formation in n-heptane/air laminar diffusion flames: Effect of toluene addition

Xiaokang Nie,Jiawei Qi,Shunjie Feng,Ya Liu,Bingbing Qiu,Huaqiang Chu

The mixture of n-heptane and toluene is regarded as surrogate fuel for diesel. Under the premise of a certain carbon flow rate , the particle size, nanostructure , microcrystalline size and soot deposition morphology of three kinds of fuel laminar diffusion flames were studied by Transmission Electron Microscopy (TEM), High Resolution Transmission Electron Microscopy (HRTEM), X-ray diffractometer (XRD) and Field Emission Scanning Electron Microscopy (FESEM). The three fuels were pure n-heptane (T0), toluene / n-heptane blends with 5 vol% (T5) and 10 vol% (T10) toluene, respectively. Thermophoretic probe sampling and SiC fiber deposition were used to obtain soot samples. The results showed that with the increase of toluene content, the flame height increased and the temperature decreased at the same height. The addition of toluene increased the content of PAHs , which promoted the formation of soot, and increased the number and particle size of soot. At HAB = 30 mm, with the increase of toluene content, the graphitization degree of soot increased, which showed a larger soot fringe length and a smaller fringe tortuosity, and microcrystalline width ( L a) of soot particles increased gradually. It is worth noting that the size of a new structure in the soot deposition is counted for the first time, and it is found that its size is negatively correlated with the fringe length and microcrystalline width of soot.

Organic Crosslinked Polymer-Derived N/O-Doped Porous Carbons for High-Performance Supercapacitor

Jianhao Lao,Yao Lu,Songwen Fang,Fen Xu,Lixian Sun,Yu Wang,Tianhao Zhou,Lumin Liao,Yanxun Guan,Xueying Wei,Chenchen Zhang,Yukai Yang,Yongpeng Xia,Yumei Luo,Yongjin Zou,Hailiang Chu,Huanzhi Zhang,Yong Luo,Yanling Zhu

Supercapacitors, as a new type of green electrical energy storage device, are a potential solution to environmental problems created by economic development and the excessive use of fossil energy resources. In this work, nitrogen/oxygen (N/O)-doped porous carbon materials for high-performance supercapacitors are fabricated by calcining and activating an organic crosslinked polymer prepared using polyethylene glycol, hydroxypropyl methylcellulose, and 4,4-diphenylmethane diisocyanate. The porous carbon exhibits a large specific surface area (1589 m2·g−1) and high electrochemical performance, thanks to the network structure and rich N/O content in the organic crosslinked polymer. The optimized porous carbon material (COCLP-4.5), obtained by adjusting the raw material ratio of the organic crosslinked polymer, exhibits a high specific capacitance (522 F·g−1at 0.5 A·g−1), good rate capability (319 F·g−1at 20 A·g−1), and outstanding stability (83% retention after 5000 cycles) in a three-electrode system. Furthermore, an energy density of 18.04 Wh·kg−1is obtained at a power density of 200.0 W·kg−1in a two-electrode system. This study demonstrates that organic crosslinked polymer-derived porous carbon electrode materials have good energy storage potential.Keywords:supercapacitor;organic crosslinked polymer;porous carbon;electrochemistry

Synergistic effects of Bi and N doped on ZnO nanorods for efficient photocatalysis

N.R. Khalid,Hamid Ishtiaq,Faisal Ali,M.B. Tahir,Sumaira Naeem,A. Ul-Hamid,M. Ikram,T. Iqbal,M. Rizwan Kamal,Hussein Alrobei,Meshal Alzaid,A. Dahshan

The fast pace of industrial growth during the current decade has seen a large family of dyes employed copiously in the production of various products such as paper and ink. These dyes pollute earth's ecosystems. Researchers look at various ways to degrade these dyes including the use of suitable nanomaterials . ZnO is an important semiconductor material that can be employed for this purpose. In this research work, we optimized the photocatalytic capability of ZnO by co-doping it with 1–7 wt% of Bi and N. The synthesized Bi and N co-doped ZnO nanorod samples showed excellent photocatalytic behavior towards Rhodamine-B (RhB). It was confirmed using XRD and SEM that (5, 2.5) wt.% Bi/N co-doped ZnO nanorods exhibited unique morphology and structure. EDX successfully assessed the elemental composition of the synthesized samples. To provide further insight into its microstructure, the HRTEM and SAED analysis were performed. Optical properties were determined using PL and UV–Visible spectroscopy. The prepared nanorod material degraded almost 89% of RhB in 180 min. The superior degradation ability of co-doped ZnO material when exposed to visible portion of sunlight spectrum is credited to the decrease in the recombination rate of charges and an increase in the depth penetration of photons. The degradation efficiency of Bi/N co-doped ZnO material is enhanced due to reduced recombination rate and increased production of number of defects and oxygen vacancies .

Co3O4/Co nano-heterostructures embedded in N-doped carbon for lithium-O2 batteries

Lei Ding,Tianyue Huang,Dawei Zhang,Pan Qi,Lihao Zhang,Cong Lin,Hao Luo

Rational design and synthesis of high-performance bifunctional oxygen electrocatalysts with increased effective active sites and facilitated mass/electron transfer are in demand for the lithium-oxygen batteries (LOBs) to overcome the sluggish oxygen reduction/evolution kinetics. Herein, a simple yet effective strategy is proposed by annealing the Prussian blue analog (PBA) precursor under altered calcination conditions to achieve the efficient nano-heterojunction catalysts with optimized active sites. As a result, the obtained porous Co 3 O 4 /Co nano-heterostructures embedded in N-doped graphitized carbon matrix (Co 3 O 4 /Co@NC) exhibit outstanding electrochemical performance with a high specific capacity of 22,156 mA h g −1 at the current density of 100 mA g −1 and excellent stability, obviously superior to the LOBs based on the other single-component catalysts. Systematic investigations suggest that the enhanced electrochemical performance is ascribed to the Co 3 O 4 /Co nano-heterostructure interface and the N-doped porous carbon matrix. This study presents a simple and effective approach for boosting the PBA-derived catalysts with efficient reactivity for various catalytic applications.

Constructing Co3O4/La2Ti2O7 p-n Heterojunction for the Enhancement of Photocatalytic Hydrogen Evolution

Haodong Wen,Wenning Zhao,Xiuxun Han

Layered perovskite-type semiconductor La2Ti2O7has attracted lots of attention in photocatalytic hydrogen evolution, due to the suitable energy band position for water splitting, high specific surface area, and excellent physicochemical stability. However, the narrow light absorption range and the low separation efficiency of photogenerated carriers limit its photocatalytic activity. Herein, plate-like La2Ti2O7with uniform crystal morphology was synthesized in molten NaCl salt. A p-n heterojunction was then constructed through the in situ hydrothermal growth of p-type Co3O4nanoparticles on the surface of n-type plate-like La2Ti2O7. The effects of Co3O4loading on photocatalytic hydrogen evolution performance were investigated in detail. The results demonstrate that composite Co3O4/La2Ti2O7possesses much better photocatalytic activity than the pure component. The composite photocatalyst with 1 wt% Co3O4exhibits the highest hydrogen evolution rate of 79.73 μmol·g−1·h−1and a good cycling stability. The photoelectrochemistry characterizations illustrate that the improvement of photocatalytic activity is mainly attributed to both the enhanced light absorption from the Co3O4ornament and the rapid separation of photogenerated electron-hole pairs driven by the built-in electric field close to the p-n heterojunction. The results may provide further insights into the design of high-efficiency La2Ti2O7-based heterojunctions for photocatalytic hydrogen evolution.Keywords:photocatalysis;hydrogen evolution;p-n heterojunction;La2Ti2O7;Co3O4

Preparation of ZSM-22/ASA composite material for enhancing n-dodecane hydroisomerization performance

Le Wang,Pengyu Niu,Hongjuan Xi,Xiaoyan Chen,Congbiao Chen,Zhongyi Ma,Litao Jia,Bo Hou,Debao Li

The ZSM-22/ASA composite material for efficient hydroisomerization of n-dodecane was successfully prepared via a two-step synthesis method. The structure, pore properties, and acidity of the catalysts were elucidated by the means of XRD , N 2 physical adsorption, TEM, FT-IR, and Py-IR. Compared with the mixture catalyst, ZSM-22/ASA has a higher average pore diameter and formed a uniform and open channel structure, which is favorable to the diffusion of the reactant and the efficiency of the acid sites. The zeolite and the ASA phase in the composite are closely bonded by the interface effect, forming an additional Si–O–Al structure, which significantly affected the acidity of the composite catalyst. ZSM-22/ASA composite material exhibits enhanced n-dodecane hydroisomerization selectivity of total isomers and multi-branched isomers, which is attributed to its proper acid strength and pore structure conducive to diffusion. Finally, the location distribution of branched methyl groups was discussed and enhanced more central branching iso-dodecanes was obtained over the ZSM-22/ASA composite material.

ZIF-67 derived Co/N carbon hollow fiber membrane with excellent decontamination performance

Jia Xie,Yingpeng Yang,Hao Zhang,Saisai Chen,Zhengjun Lv,Yujun Zhou,Junwen Qi,Xiuyun Sun,Jiansheng Li

Advanced oxidation processes (AOPs) were appealing wastewater treatment options yet practices were hampered by reactor design and diminished performance in complex water matrices. Herein, one-step-pyrolysis strategy was proposed for large-scale synthesis of ZIF-67 derived conductive Co/N carbon hollow fiber ultrafiltration membrane to achieve exceptional availability of catalytic sites and interference prevention from macro molecular substances by size exclusion. Benefitting from the microenvironment modulation and electric field assistance (−1 V, membrane as the cathode), the bisphenol A (as a model micropollutant) can be efficiently removed with enhanced mass transfer of flow-through process (modified apparent reaction rate constant of 1260 μM g cat -1 s −1 ) and the active cobalt species were cycled via electroreduction thus showing exceptional sustainability with nearly zero Co leaching even after 24 h operation. The synergy effects between separation and catalysis alleviated the deteriorated AOPs efficiency and membrane fouling caused by macromolecular organic matter. The integrated membrane system provides new insight into rational design of catalytic membrane and system engineering for advanced water purification.

Copper-Promoted One-Pot Sandmeyer-Type Reaction for the Synthesis of N-Aryltriazoles

Menghan Cui,Rong Wang,Qing Yang,Chunxiang Kuang

Herein, we report the copper-catalyzed one-pot Sandmeyer-type reaction of aromatic amines with triazoles to afford N-aryl-1,2,3-triazoles. Diazonium salts, formed from aromatic amines and tert-butyl nitrite in the presence of fluoroboric acid, reacted with triazoles in a copper-catalyzed Sandmeyer-type reaction. The reaction proceeded under mild conditions to afford N-aryltriazoles in moderate to good yields. This method is amenable to a wide range of aromatic amines and triazoles and shows diverse functional group tolerance. Inhibition of the reaction upon the addition of free radical scavengers suggested a radical pathway, in which the aryl radical, copper, and triazole formed a complex that underwent reductive elimination to give aryltriazole compounds; this is consistent with the mechanism underlying the Sandmeyer reaction. Thus, we demonstrate a new effective strategy for the construction of C–N bonds via Sandmeyer-type reactions and a valuable alternative approach for the synthesis of aryltriazole derivatives.

Surface-Confined Synthesis of Ultrafine Pt-Rare Earth Nanoalloys on N-Functionalized Supports

Mingzhen Hu,Zengjian Cai,Xinhu Liang,Ganggang Li,Haiyan Tan,Shitu Yang,Hao Ren,Zhe Wang,Guodong Sun,Shoujie Liu,Zhengping Hao,Kebin Zhou

It is extremely challenging to controllably synthesize rare earth-containing nanoalloys due to the ultralow standard reduction potential of rare earth metals. Here, a surface-confined strategy to prepare ultrafine Pt-rare earth nanoalloys on a series of N-functionalized supports is reported. It proves that by surface N-metal coordination, the metal cations of precursors are atomically dispersed on support, which greatly favors uniform nucleation and growth of particles upon reduction. Moreover, the moderate metal transfer barrier from N ensures particle growth in a confined region to form ultrafine nanoalloys. Using this method, ultrafine Pt  La, Pt  Y, and Pt  Dy nanoalloys are prepared on N-functionalized supports such as carbon, zeolite, and Al 2 O 3 . Notably, the Pt  La nanoalloys on N-functionalized zeolite show superior activity and durability for propane oxidation. The strategy is expected to provide guidelines for preparing highly efficient rare earth-containing nanoalloys for catalysis applications.

ReaxFF molecular dynamics simulations of n-eicosane reaction mechanisms during pyrolysis and combustion

Wenjuan Li,Shuo Yu,Liang Zhang,Jianfa Chen,Weiguo Cao,Yanhua Lan

The pyrolysis and combustion mechanism of the hydrocarbon fuel has important scientific and practical significance. However, it is difficult to detect the whole intermediates and products using traditional methods, which brings trouble to the analysis of the reaction process. In this paper, the microscopic reaction mechanism and the main products of n- eicosane (C 20 H 42 ) were simulated based on the reactive force field molecular dynamics (ReaxFF-MD). The effects of temperature (2000–3500 K) and oxygen on the initial decomposition, the distribution of main products, and the reactive pathways of C 20 H 42 fuel were studied to determine its reaction mechanism. The initial decomposition of C 20 H 42 was mainly initiated by small alkyl radicals in pyrolysis, and by the oxygen-containing radicals in combustion. The participation of oxygen had a greater effect on accelerating the decomposition reaction . The reactions involving oxygen of C 20 H 42 initial decomposition accounted for 87.5% of the total reactions at 2000 K. Moreover, the detailed distribution and formation pathways of the main products of H 2 , C 2 H 4 , CH 4 , H 2 O, CO, and CO 2 were depicted to construct the overall reaction mechanism of C 20 H 42 . •H radical formed from the composition of C 2 H 4 was exactly consistent with the •H radical consumed by the generation of CH 4 and H 2 in the pyrolysis stage. The feasibility of the simulation method was verified by the result of thermal analysis. The results are helpful for further research on the reaction mechanism of hydrocarbon fuels.