科创中国

Two-dimensional CdS micro/nano leaves have been synthesized via a controlled hydrothermal process. The dimensions of the leaves is in the range of 4-6 μm and the thickness of the leaves is 30-50 nm. The surface of the leaves is smooth and composed of several parallel laminar layers with multi-steps. The SAED and HRTEM images indicated that the surface of the leaves was mainly composed of (0001) plane and all the leaves had single-crystallinity. The morphology of the as-prepared products could be controlled by adjusting the concentration of hydrofluoric acid (HF). The effects of HF concentration, reaction temperature and time were investigated. A possible formation mechanism is proposed based on the intrinsic crystal structure and selected adsorption processes. In addition, the as-prepared CdS pinnate leaves showed enhanced photocatalytic activity toward hydrogen evolution under visible light irradiation. The efficiency of micro/nano leaves was more than 6 times greater than normal CdS microparticles.

Cuixia Li;Lijun Han;Rongji Liu;Honghua Li;锁江 张;Guangjin Zhang

Journal of Materials Chemistry

2012-12-7

The understanding of confined structure and flow property of ionic liquid (IL) in a nanochannel are essential for the efficient application of ILs in the green chemical processes. In this work, the ionic structure and various flow behaviors of ILs inside graphene nanochannels via molecular dynamics simulations are shown. The effect of the nanochannel structure on confined flow is explored, showing that the width mainly heightens the viscosity while the oxidation degree primarily enhances the interfacial friction coefficient. Tuning the width and oxidation degree of nanochannel, three different flow behaviors including Poiseuille, partial plunger and full plunger flow can be achieved, where the second one does not occur in water or other organic solvents. To describe the special flow behavior, an effective influence extent of the nanochannel (w _EIE) is defined, whose value can distinguish the above flows effectively. Based on w _EIE, the phase diagrams of flow behavior for the nanochannel structure and pressure gradient are obtained, showing that the critical pressure gradient decreases with width and increases with the oxidation degree. Based on the quantitative relations between confined structures, viscosity, friction coefficient, flow behavior, and nanochannel structure, the intrinsic mechanism of regulating the flow behavior and rational design of nanochannel are finally discussed.

Yanlei Wang;Chenlu Wang;Yaqin Zhang;Feng Huo;Hongyan He;锁江 张

Small

2019-7-19

In this work, metal acetylacetonates were used to catalyze the reaction of dimethyl carbonate (DMC) and bisphenol A (BPA) and high conversion of BPA and excellent selectivity of carboxymethylation products were achieved. Among these, zirconium(IV) acetylacetonate (Zr(acac)4) exhibited the best catalytic performance with BPA conversion of 85.2% and carboxymethylation products selectivity up to 99.0%, which has been the most efficient catalyst so far to the best of our knowledge. According to Fourier transform infrared (FT-IR) characterization and density functional theory (DFT) calculations, we found that the most active cis-cis interaction species 3 formed between a Zr cation and two oxygen atoms from the CH3-O moiety of DMC greatly promoted the selective occurrence of the carboxymethylation reaction. It was demonstrated that the catalytic performance of metal acetylacetonate was related to d-electrons and interaction mode of the metal, and the plausible reaction mechanism was proposed.

Hongzhe An;Zifeng Yang;Kailun Bi;Fei Xu;Feng Huo;Chenhao Li;Wenjuan Fang;Zhencai Zhang;Xingying Lan;锁江 张

Industrial & Engineering Chemistry Research

2020-8-5

Carbohydrates were found to have substantial effects on tailoring phase tunable of ionic liquids (ILs) and water. Phase behaviors of 1-alkyl-3-methylimidazolium derivatives [C_nmim]X (n = 2 to 10, X = Cl^-, Br^-, BF₄^-)-carbohydrate-H₂O were systemically investigated. For hydrophilic ILs, 1-alkyl-3-methylimidazolium tetrafluoroborate [C_nmim]BF₄ (n = 3, 4), the homogeneous aqueous solution can be induced to separate two aqueous phases by addition of carbohydrate. For hydrophobic ILs, [C_nmim]BF₄ (n = 5 to 10), the mutual solubility with water can be lowered by addition of carbohydrate. While 1-alkyl-3-methyl imidazolium chloride ([C_nmim]Cl, n = 2 to 10) and 1-alkyl-3-methyl imidazolium bromide ([C_nmim]Br, n = 2 to 10) aqueous solutions never form aqueous two-phase systems (ATPSs) with carbohydrate in the investigated temperatures ranging from (242.15 to 373.15) K. The high partitioning behavior of phenol in [C_nmim]BF₄ (n = 3 to 10) (1) + carbohydrate (2) + H₂O (3) shows that carbohydrate-tailored {IL + H₂O} systems are feasible to be used as extraction systems, especially in biological and environmental engineering.

Yuhaun Chen;Yige Wang;Qingyan Cheng;Xiaoli Liu;锁江 张

Journal of Chemical Thermodynamics

2009-9

A Co^II/CF₃COOH (TFA)-catalyzed oxidative esterification of aldehydes and alkanols by using tBuOOH as an oxidant is reported. A mechanistic investigation indicated that the oxidation reaction proceeded through the formation of a Co^III−OCH(OMe)R complex, followed by H-atom abstraction by an in-situ-generated tBuO^. radical. The former kinetic step was thought to be the selectivity-determining step. Moreover, the strong acidity and TFA proton were beneficial for both the dehydrative formation of the Co^III−OCH(OMe)R complex and the redox properties of the cobalt atom, thereby offering high efficiency for the target oxidative cross-coupling reaction.

Sajid Mahmood;Ting Li;Bao Hua Xu;Ya Fei Guo;锁江 张

Asian Journal of Organic Chemistry

2017-6

Electrodeposition of aluminum from ionic liquids has been considered a promising approach to low-temperature aluminum electrolysis. In this study, we first investigated the electrochemical stability of 1-ethyl-3-methylimidazolium chloride ([Emim][Al₂Cl₇]) electrolyte, which is a typically used electrolyte for aluminum electrodeposition. It was found that part of imidazole ions decomposed on the cathode during the electrolysis process, especially when the temperature was at or over 353 K. In order to enhance the stability of the electrolyte, we further studied the effects of lithium salt and lithium bis(oxalato)borate (LiBOB), on the electrochemical stability of the [Emim][Al₂Cl₇] ionic liquid system. It was found that the electrochemical window of the electrolyte was broadened from 2.59 to 2.74 V at 373 K by addition of 1 mol% LiBOB. With the existence of LiBOB, the reduction current density of Al₂Cl₇ ^- increased before −0.58 V and the electrodissolution of Al was more complete. The possible mechanism on the LiBOB increases the stability of the electrolyte systems also discussed based on our theoretical calculations.

Haiyan Lang;Junling Zhang;Yanhong Kang;Shimou Chen;锁江 张

Ionics

2017-4-1

Thiol-ene materials are a series of materials that can be crosslinked using a suitable photo-initiator and a UV light source. An advantage of thiol-ene materials is that they can be tailored to have specific mechanical properties by controlling the stoichiometry of the mixtures. By combination of different reactants, it is therefore, in principle, possible to prepare monoliths with greatly varying mechanical properties from essentially the same material. In this paper, we prepared an alternating hard and soft thiol-ene material with a sharp solid interface. Tetrakis (3-mercaptopropionate) (PETMP) with 1, 3, 5-triallyl-1, 3, 5-triazine-2, 4, 6(1H, 3H, 5 H)-trione (TATATO) as the hard segment exhibited strong tensile and compressive strength but had low elongation and weak bending stiffness. A mixture of PETMP and trimethylolpropane diallyl ether (TMPDE) was selected as the soft segment. After stretching at 0.001 s⁻¹ using a filament stretching rheometer (FSR), the soft segment fractured at the strain of 21%, while the interface of the materials was strong enough to prevent cracking.

Peng Shen;Saeed Zajforoushan Moghaddam;Qian Huang;Anders Egede Daugaard;锁江 张;Peter Szabo

Materials Today Communications

2019-12

The desirable properties of room temperature ionic liquid (RTIL) with low heat capacity, low corrosive, nonvolatile and good CO₂ solubility make it possible to tailor the amine aqueous solution for capture of CO₂ with low energy consumption. However, the detailed thermal analysis, which is helpful for understanding deeply the energy saving potential for ionic liquids (ILs)-based solvent, is scant. In this work, three different ILs with the same cation, 1-butyl-3-methylimidazolium ([Bmim]), and different anions, including tetrafluoroborate ([BF₄]), nitrate ([NO₃]), chloride ([Cl]), are used to tailor the N-methyldiethanolamine/piperazine (MDEA/PZ) aqueous solution to assess their role in CO₂ capture performance. The results showed that the investigated ILs affect the physical solubility of CO₂. Adding [Bmim][BF₄] into MDEA/PZ showed the largest CO₂ cyclic capacities, whereas, it is the smallest for MDEA/PZ/[Bmim][NO₃], which indicates that anion species of the ILs could tune the sensible heat. Based on the calorimeter measured results and modeling estimated results, the reaction enthalpy changes with the addition of different ILs were also observed. The addition of [Bmim][BF₄] could reduce the average enthalpy of CO₂ dissolution and the sensible heat at 313K by 30.1% and 20.3%, respectively. Finally, the studies revealed that not only the latent heat of vaporization but also the sensible heat and reaction heat of CO₂ capture can be tailored by the choice of ILs.

Jubao Gao;Lingdi Cao;Haifeng Dong;香平 张;锁江 张

Applied Energy

2015-9-5

It is important to find an effective way to separate lithium from the mother liquor obtained by the reaction of lithium chloride/lithium sulfate and sodium carbonate. A synergistic solvent extraction system containing 1-phenyl-3-heptyl-1,3-propanedione (PHPD) and liquid mixture of trialkyl-phosphine oxides (Cyanex923) to separate lithium from the system of Li ⁺ +Na ⁺ +Cl ^- +CO ₃ ^2- +H ₂ O was developed. The pH of the aqueous solution showed an important effect on the lithium extraction. At pH 13.06, PHPD alone showed a high extractability of lithium, but the addition of Cyanex923 led to a high separation ability of lithium over sodium due to the synergistic extraction effect. For a single extraction, the extraction percentage of lithium was 97.83% from the solution with 1.39 g·L ^-1 Li and 68.97 g·L ^-1 Na using the extraction system containing 0.4 mol·L ^-1 PHPD and 0.2 mol·L ^-1 Cyanex923 at the A/O ratio of 1:1, initial aqueous pH of 13.06, and 293.15 K, and the separation factor of lithium over sodium reached 475.06. On the basis of the McCabe-Thiele diagram of lithium extraction, two stages need to be used to achieve the complete extraction of lithium with an A/O ratio of 1.8. The extracted lithium species obtained by the slope analysis method were LiES and LiES ₂ , where E and S represent the deprotonated PHPD and Cyanex923, respectively. The electrospray ionization mass spectra (ESI-MS) further confirmed that another two main Li adducts existing in the organic phase were LiE and LiE(H ₂ O). The extracted lithium could be completely stripped from the loaded organic solution with hydrochloride of 0.5 mol·L ^-1 at an A/O ratio of 1:1. All of these will provide a theoretical basis for lithium separation from the mother liquor obtained during the process of lithium carbonate production.

Junfeng Wang;Shicheng Yang;Ruibing Bai;Yongmei Chen;锁江 张

Industrial & Engineering Chemistry Research

2019-1-23

Silicon is considered as a promising anode material to improve the energy density of lithium ion batteries. However, the huge capacity loss in the initial cycles not only consumes the active Li from the cathode, but also shows great influence on the long-term cycle stability for the varied negative/positive capacity ratio (N/P ratio) that may lead to over-charge/discharge, thus hinders silicon from commercial application. Therefore, it's of vital importance to study the N/P ratio to realize the tradeoff between initial coulombic efficiency (ICE) and cycling stability. LiNi_0.8Co_0.15Al_0.05O₂||SiO_x/Graphite pouch cells with different N/P ratios between 0.85 and 1.8 are designed and prepared in this paper, electrochemical tests prove that a N/P ratio close to unity provide the best balance between energy density and cycle performance. Moreover, capacity decay mechanisms in cathode and anode are carefully studied, which demonstrates that up to 90% of the capacity loss is due to the active Li host sites loss in anode, while the crosstalk between the two electrodes also must be considered.

Zhan Chen;Lan Zhang;Xiangkun Wu;Kaifang Song;保增 任;Tao Li;锁江 张

Journal of Power Sources

2019-11-1