查找使用阿拉丁产品的科研文献

N-doped graphitized porous carbon derived from N-rich polymer for improved supercapacitor performance

Jianqing Bian,Mengmeng Zheng,Qibin Chen,Honglai Liu

Porous carbons with the large specific surface area, high electrical conductivity as well as abundant heteroatom doping are regarded as a promising candidate for supercapacitor applications. In this report, a facile potassium ferrate (K2FeO4) activation strategy is adopted to transform the N-rich Schiff-based polymer into N-doped graphitized porous carbons (NGPCs) by the synchronous activation and graphitization. The optimized NGPC-700-1 sample delivers a delightful capacitance of 322.7 F g−1 at 0.5 A g−1 and an excellent rate capability (79.1% capacitance retained at 50 A g−1) in 6 M KOH due to the unique laminated and porous structure with the large surface area (2123.7 m2 g−1), high porous volume (1.30 cm3 g−1) and abundant N/O dopant (6.20/8.20 at%). Moreover, the assembled symmetric supercapacitor achieves a high energy density of 21.5 W h kg−1 at the power supply of 445.5 W kg−1 in 1 M Na2SO4 electrolyte. Therefore, NGPCs derived from one-step activation/graphitization of N-rich polymer represent a promising route for preparing porous carbon materials with the high charge storage capacity and rate capability in the energy storage.

Ti2+ Site-Promoted N≡N Bond Activation in LaTiO3–x Nanosheets for Nitrogen Photofixation

Mengyang Xia,Ben Chong,Xiangjiao Gong,Hang Xiao,He Li,Honghui Ou,Bin Zhang,Guidong Yang

Using solar energy to fix N2 and produce NH3 is a promising route. For nitrogen photofixation, the transition-metal active site in the low oxidation state is conducive to the adsorption of N2, but it is often difficult to further dissociate N2, restricting the reaction. Therefore, it is necessary to precisely modulate the electron energy level of the active site to couple with the molecular orbitals of N2, thus reducing the energy barrier of N2 dissociation. Here, the perovskite-type LaTiO3–x with an ultralow oxidation state Ti2+ site is achieved via in situ modulation of phase transition and defect engineering. The obtained Ti2+ sites could inject more d-orbital electrons into the N2 π* antibonding orbitals to achieve N2 activation and dissociation. Therefore, compared with pristine La2Ti2O7 and La2Ti2O7–x samples without ammonia production activity, LaTiO3–x samples showed a remarkable performance for photocatalytic N2 fixation. The NH3 generation rate reached up to 107 μmol gcat–1 h–1 after the 1st hour, and the average NH3 generation rate after 4 h was approximately 51.5 μmol gcat–1 h–1. Furthermore, in situ characterization and density functional theory (DFT) calculations revealed the role of Ti sites with different oxidation states (Ti4+, Ti3+, Ti2+) in N2 activation, which would provide a unique perspective for designing efficient N2 fixation catalysts.

Thermal conductivity measurements for n-nonane and n-undecane at elevated temperature and pressure

Shuo Yuan,Yi Liu,Jingwei Cui,Xiong Zheng

Hydrocarbons have wide applications in various industrial processes, and the knowledge of thermophysical properties is the foundation for their utilization. As an important thermophysical property, the thermal conductivity of fluids is vital in the evaluation of energy conversion quality, like heat transfer enhancement , thermodynamic cycle efficiency evaluation, etc. Therefore, obtaining accurate experimental data is of great importance for the utilization of hydrocarbons. Here, the thermal conductivities of liquid n-nonane and n-undecane were investigated using the transient hot-wire method (combined expanded uncertainty is 2.0 %) with a wide temperature and pressure range from 293.15 to 523.15 K and 0.1 to 15.0 MPa. For the convenience of engineering applications, a polynomial as a function of temperature and pressure was proposed to correlate the experimental data, the average absolute deviations between experimental data and fitted data are 0.29 % for n-nonane and 0.35 % for n-undecane, which indicates that the polynomial describes the experimental data well in the measured region. Meanwhile, the available literary data were collected and compared with our results, and good agreement was found between literary data and our results. This work is not only helpful for the industrial applications of hydrocarbons but also helps to understand the internal mechanism of the thermal conductivity of hydrocarbons.

0D/2D CdS/ZnO composite with n-n heterojunction for efficient detection of triethylamine

Jingjing Liu,Bicheng Zhu,Liuyang Zhang,Jiajie Fan,Jiaguo Yu

It is imperative to seek for novel materials with pronounced gas sensing performance towards triethylamine for the sake of human health. Herein, we successfully fabricate an outstanding triethylamine sensor based on CdS/ZnO composite with 0D/2D structure, which are prepared by in-situ growth of CdS quantum dots on ultra-thin ZnO nanosheets . The ratios between the two ingredients are adjusted and their effect is evaluated. The optimal sample exhibits the lowest operating temperature of 200 °C, the highest response value of ~20 and the fastest response time of 2 s. Besides, it also has the virtues of durable stability, excellent selectivity and superior anti-interference ability. The mechanism behind the aforementioned intriguing performance is investigated by X-ray photoelectron spectroscopy, Kelvin probe and density function theory (DFT) simulation. All the results verify that the enhanced gas sensing properties are derived from splendid 0D/2D structure, n - n heterojunction and large specific surface area. Additionally, this study opens an avenue for designing sensors with 0D/2D structure.

Mg(ClO4)2-N,N-Dimethylformamide (Acetonitrile)/NaCl Double Electrolytes for Magnesium–Air Batteries

Ma Jingling,Jia Xingliang,Ma Mingsheng,Zhang Chenfei,Ren Fengzhang,Wang Guangxin

To limit corrosion and retain activity of magnesium anode, magnesium–air batteries with double solutions: 0.5 M Mg(ClO 4 ) 2 - N , N -dimethylformamide (DMF)/0.6 M NaCl-H 2 O, 0.5 M Mg(ClO 4 ) 2 –acetonitrile (AN)/0.6 M NaCl-H 2 O are prepared. Cathodic and anodic reactions proceed in inorganic and organic solutions separately. Discharge performance, discharge morphology, and corrosion behavior of magnesium anode are researched. Results obtained show that organic electrolytes separate anode from the aqueous electrolyte, thus improving anode utilization rate. Due to 0.6 M NaCl solution used in air cathode side, the batteries show higher discharge voltages. A better discharge performance has been observed in double electrolytes at 1 mA·cm −2 discharge. Results of discharge morphology and electrochemical impedance spectroscopy agree well with discharge performance. The discharge mechanism of magnesium anode in different solutions is also discussed.

Supramolecular assemblies controlled by cucurbit[n]uril size (n = 6, 7, 8 and 10)

Weitao Xu,Xinyu Deng,Xin Xiao,Bing Bian,Qing Chen,Scott J. Dalgarno,Zhu Tao,Carl Redshaw

A benzyl substituted 4-pyrrolidinopyridinium salt (G) with multiple active sites including benzyl, pyridinium and pyrrole groups has been synthesized. The interaction between G and a series of cucurbit[n]urils (TMeQ[6], Q[7], Q[8], Q[10]), has been studied both in aqueous solution and in the solid state. The binding interaction site between G and the Q[n] can be controlled by the size of the cavity of the Q[n]s. In the case of TMeQ[6], the benzyl is accommodated within the cavity, whilst for Q[7] and Q[8], the pyrrole ring and the benzyl are accommodated within the cavity of the Q[7/8], and the latter can shuttle on the guest G in a state of dynamic equilibrium. For the larger cavity of Q[10], the entire G molecule is located within the cavity of the Q[10].

Physicochemical properties of switchable-hydrophilicity solvent systems: N,N-Dimethylcyclohexylamine, water and carbon dioxide

Jian Wang,Yongqin Du,Cunbin Du,Anli Xu,Ganbing Yao,Hongkun Zhao,Xuedong Zhu,Xuhong Guo

For switchable hydrophilicity solvent (SHS) systems ( N,N -Dimethylcyclohexylamine (DMCA), water, and carbon dioxide): the density, viscosity, refractive index and conductivity at (283.15–308.15) K and 0.1 Mpa, were measured. The apparent molar volumes were determined as a function of composition at each temperature from experimental data. Based on Masson’s equation limiting apparent molar volumes and Masson’s coefficient S V describing the character of interactions were calculated. The relative viscosity values were adjusted to obtain the viscosity B coefficients and dB/dT values. It has been observed that there exist strong solute-solvent and solute-solute interactions in these systems, and DMCAH-bicarbonate salt acts as structure-maker in aqueous solvent.

Highly reactive N,N′-carbonyldiimidazole-tailored bifunctional electrocatalyst for oxygen reduction and oxygen evolution

Wen-Li Xin,Kun-Kun Lu,Dun-Ru Zhu,Hai-Bo Zeng,Xue-Ji Zhang,Robert-S. Marks,Dan Shan

The rational design and synthesis of an efficient bielectrocatalyst for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) by tuning the chemical composition , structure and the catalytic sites of the hybrid materials is always of a great challenge. In this work, an innovative strategy based on the highly active N,N′-carbonyldiimidazole (CDI) is described to one-pot synthesis of a novel precursor for bifunctional O 2- electrocatalyst . The coordination of Co 2+ with the in situ generated ligands imidazole and carbonate results in ultrafine cobalt carbonate (CoCO 3 )-involved cobalt-based zeolitic imidazole framework (CoCO 3 /Co-ZIF). Owing to the presence of ultrafine CoCO 3 , carbonization of CoCO 3 /Co-ZIF at 800 °C under N 2 atmosphere endows the pyrolysis product with a special skeleton of carbon nanotube (CNT)-tipped end CoO x , multivalent CoO x wrapped in graphitic carbon layers. Thus, the resulting CoO x /Co-N-C exhibits the enhanced and durable ORR/OER performance in alkaline media, due to the fast electron and mass transfers. For ORR, a large limiting current density of 4.59 mA cm −2 can be obtained by CoOx/Co-N-C, which is comparable to that of Pt/C. For OER, it only needs an over potential of 1.65 V to achieve a current density of 10 mA cm −2 , merely 30 mV behind IrO 2 (1.62 V).

The effect of N-ethyl-N-hydroxyethyl perfluorooctanoamide on wettability alteration of shale reservoir

Li Yongfei,Wang Yanling,Wang Kun,Gomado Foster,Wang Gangxiao,Tang Longhao,Rong Xufeng

The wettability of the formation is critical for the flow back of the fracturing fluid and can further affect the gas production. So it is very necessary to study the wettability of shale reservoir. Here, a novel fluorocarbon surfactant, N-ethyl-N-hydroxyethyl perfluorooctanoamide, was synthesized and characterized by different methods. the contact angles of water and n-decane on the shale increased from 36° and 0° to 121° and 105°, respectively, after treated by N-ethyl-N-hydroxyethyl perfluorooctanoamide (0.5 wt.%). The surface free energy reduced from 72 mN/m to 7.4 mN/m. The results agreed with that of imbibition and capillary tube rise test. Additionally, the analysis of scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) showed that the roughness of shale surface remarkably increased. These results fully proved that the shale wettability is changed to super gas-wetting. Besides, the thermal analysis revealed that the novel fluorocarbon surfactant has good thermal stability. This indicates that it can be better applied to reservoir modifications at higher temperatures.

Spectrophotometric determination of trace permanganate in water with N,N-diethyl-p-phenylenediamine (DPD)

Xin Liu,Huahua Cai,Jing Zou,Zijun Pang,Baoling Yuan,Zhenming Zhou,Qingfeng Cheng

A sensitive spectrophotometric method (the N,N -diethyl- p -phenylenediamine (DPD) method) was established for the determination of trace permanganate concentration (0–10 μM) in water. The DPD method was based on the oxidative coloration reaction where permanganate could oxidize DPD to form the red colored DPD radical (DPD • + ) with a second-order rate constant of 2.96 × 10 4  M −1  s −1 at pH 6 (50 mM phosphate buffer). The generated DPD • + could be quantitatively measured at 551 nm using an UV–Vis spectrophotometer. There was a good linear relationship (R 2  = 0.999) between the absorbance of DPD • + and permanganate concentration. The DPD method was highly sensitive, and the absorbance of generated DPD • + at 551 nm was as high as 5.70 × 10 4  cm −1 per M (mol L −1 ) of permanganate. The reaction of permanganate with DPD in the pH range of 4.0–8.0 had a stoichiometric coefficient of 1:2.71. The residual absorbance of DPD •+ in ultrapure water and natural waters was fairly stable for 30 min. Limits of detection of the proposed DPD method in ultrapure water and natural waters were calculated to be as low as 0.010 μM and 0.017 μM, respectively. Moreover, trace permanganate concentrations of 0.04 and 0.10 μM were found in natural waters and wastewater by the proposed DPD method. Additionally, the DPD method could be applied to measure the second-order rate constants of the reaction of permanganate with phenol at pH 7.0 (28.2 M −1  s −1 ).

CO2 responsive wormlike micelles based on sodium oleate, potassium chloride and N,N-dimethylethanolamine

Jinyu Wang,Dongfang Liu,Zhiyu Huang,Cunchuan Zheng

Design, synthesis, bioactivity and action mechanism of N-substituted N′-phenylpicolinohydrazides against phytopathogenic fungi

Zhang Yuhao,Bai Ruofei,Du Tengyi,Wang Yiwei,Zhou Bohang,Zhou Congwei,Zhou Le

N ′-phenylpicolinohydrazide has been proven to be a promising lead compound for research and development of novel fungicides for agriculture in our previous study. As our continuing research, in this study, a series of N -substituted derivatives of N ′-phenylpicolinohydrazide were synthesized and explored for the inhibition activity on nine phytopathogenic fungi and action mechanism. The results found that eleven of the compounds had excellent antifungal activity with more than 80% inhibition rates at 50 µ g/mL on part or most of the fungi, especially A. solani and P. piricola . Compounds 5i , 5j and 5k showed EC 50 values of < 8.0 µg/mL against A. solani superior to positive control carbendazim (EC 50  = 36.0 µg/mL) while 5p and 5q exhibited the highest activity with EC 50 values of 2.72 and 2.80 µg/mL against P. piricola superior to positive control boscalid (EC 50  > 50.0 µg/mL). Furthermore, 5k also showed significant protective effect against A. solani infection on tomatoes in a concentration-dependent manner. Action mechanism research showed that 5k was able to increase the intracellular ROS level, change both MMP and permeability of cell membrane and damage mycelial morphology. Molecular docking studies showed that 5k could bind into ubiquinone-binding region of succinate dehydrogenase by hydrogen bonds, π-cation, π–π stacked, π-alkyl, and alkyl interactions. Additionally, the antibacterial activity was also investigated. Thus, N -substituted derivatives of N ′-phenylpicolinohydrazide were emerged as novel and highly promising antifungal molecular skeletons to develop new fungicides for crop protection. Graphic abstract