ACS Nano
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2023
·
IF 17.1
Shiyong Chu,Caoyang Shao,Jiaming Tian,Jingyang Wang,Yuan Rao,Chengrong Xu,Haoshen Zhou,Shaohua Guo
Layered oxides are widely accepted to be promising cathode candidate materials for K-ion batteries (KIBs) in terms of their rich raw materials and low price, while their further applications are restricted by sluggish kinetics and poor structural stability. Here, the high-entropy design concept is introduced into layered KIB cathodes to address the above issues, and an example of high-entropy layered K0.45Mn0.60Ni0.075Fe0.075Co0.075Ti0.10Cu0.05Mg0.025O2 (HE-KMO) is successfully prepared. Benefiting from the high-entropy oxide with multielement doping, the developed HE-KMO exhibits half-metallic oxide features with a narrow bandgap of 0.19 eV. Increased entropy can also reduce the surface energy of the {010} active facets, resulting in about 2.6 times more exposure of the {010} active facets of HE-KMO than the low-entropy K0.45MnO2 (KMO). Both can effectively improve the kinetics in terms of electron conduction and K+ diffusion. Furthermore, high entropy can inhibit space charge ordering during K+ (de)insertion, and the transition metal–oxygen covalent interaction of HE-KMO is also enhanced, leading to suppressed phase transition of HE-KMO in 1.5–4.2 V and better electrochemical stability of HE-KMO (average capacity drop of 0.20%, 200 cycles) than the low-entropy KMO (average capacity drop of 0.41%, 200 cycles) in the wide voltage window.
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高影响因子
FUEL
·
2023
·
IF 7.4
Deng Zhao,Haoyuan Feng,Yu Wang,Fei Wang,Huashan Wang,Hua Liu,Hui Liu
The influence mechanism of alkali metal potassium (K) on cellulose pyrolysis is a vague and fundamental key topic in the field of biomass thermal conversion. In this study, the pyrolysis of cellulose and K-impregnated cellulose was compared by in-situ DRIFTS (Diffused Reflectance Infrared Fourier Transform Spectroscopy) and TG (Thermal Gravimetric)–MS (Mass Spectrum) experiment, and quantum chemical calculations were used to verify the peak position and pyrolysis mechanism of infrared (IR) spectroscopy. Stepwise isothermal in-situ DRIFTS was designed to study the reaction path at high temperatures. It was found that in the early stage of pyrolysis, K accelerated the activation of cellulose by attacking the hydrogen bond (H-bond) in the crystal structure of cellulose, increased the dehydration rate between molecules, and promoted the decomposition of cellulose. Simultaneously, it weakened the epoxy–ether bond, inhibited the formation of dehydrated sugar, and promoted the formation of furan. Subsequently, K combined with carbonyl groups to form C–O–K structures, which improved the thermal stability of certain oxygen-containing functional groups such as carbonyls/aldehydes, so that these structures were retained until higher temperature. K promoted the conversion of dehydrated sugars to straight-chain ketones/aldehydes, which led to an increase in carbon conversion. During the coke generation stage, K promoted the formation of disordered carbon and residues, thereby inhibiting coke aromatization. The isothermal in-situ DRIFTS method proposed in this study was demonstrated to better inhibit the high temperature drift of IR spectrum during pyrolysis. It clarified the conversion between functional groups at high temperatures, which is expected to promote the development of other high-temperature pyrolysis mechanism.
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JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
·
2023
·Vol. 128
·期 24
·e2023JD039971
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IF 4.4
Lanxiadi Chen,Soleil E. Worthy,Wenjun Gu,Allan K. Bertram,Mingjin Tang
Mineral dust is one of the most abundant types of ice nucleating particles in the atmosphere. During atmospheric transport, mineral dust particles can become coated with inorganic and organic solutes, which can impact their ice nucleation activity. Aminium cations formed from amines are one type of organic solute that can coat mineral dust particles in the atmosphere, but their effects on the ice nucleation activity of mineral dust have not been studied. We investigated the effects of primary, secondary, and tertiary aminium cations with methyl and ethyl groups, as well as ammonium cations, on the ice nucleation activity of K-feldspar, an important type of mineral dust, in the immersion freezing mode at low cation concentrations (0.2–20 mM) using a droplet-freezing apparatus. Ammonium cations substantially increased the ice nucleation activity of K-feldspar, consistent with previous studies. In contrast, primary aminium cations significantly reduced K-feldspar ice nucleation activity, and secondary and tertiary aminium cations had no significant effect (the effect was less than the uncertainty of our measurements). Our combined results are consistent with the following mechanisms: ammonium cations undergo ion exchange with K-feldspar, providing exposed N–H groups for hydrogen bonding with ice; primary aminium cations undergo ion exchange with K-feldspar, exposing a hydrophobic tail that is not effective at nucleating ice; secondary and tertiary aminium cations do not undergo ion exchange with K-feldspar due to steric effects caused by the multiple hydrophobic groups on the cation. Key Points Ammonium cations significantly increased the ice nucleation activity of K-feldspar Primary aminium cations substantially reduced the ice nucleation activity of K-feldspar Secondary and tertiary aminium had limited effects on the ice nucleation activity of K-feldspar due to their inability for ion exchange Plain Language Summary Ice nucleating particles are particles in the atmosphere that can initiate the formation of ice in liquid clouds, impacting cloud properties, precipitation, and climate. Mineral dust is a dominant type of ice nucleating particles in the atmosphere. During atmospheric transport, aminium cations, formed from amine gases which can be abundant in the atmosphere, can coat mineral dust particles altering their ability to nucleate ice. However, the effect of aminium cations on the ice nucleation ability of mineral dust particles has not been studied. We investigated the effects of aminium and ammonium cations on the ice nucleation ability of K-feldspar, an important type of mineral dust and ice nucleating particles in the atmosphere. Our results show that secondary and tertiary aminium cations have no effect on the ice nucleating ability of K-feldspar, but primary aminium cations greatly reduce the ice nucleating ability of K-feldspar. This has possible implications for predicting cloud formation in the atmosphere. We also present a mechanism related to ion exchange that can explain our ice nucleation results.
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Journal of Materiomics
·
2023
·
IF 9.4
Jian Guo,Xinrui Yang,Yulong Yang,Shuting Pang,Shan-Tao Zhang,Bin Yang
Ferroelectric Sr 0.6 Ba 0.4 Nb 2 O 6 (SBN) shows typical unfilled tetragonal tungsten bronze structure where 1/6 A sites and all C sites are unoccupied. The presence of such structural vacancy provides the possibility to further modulate the crystal structure and electrical properties. In this work, alkali ions (Li + , Na + , K + ) doped SBN ceramics have been fabricated via solid-solution reaction method. In general, each doping promotes the crystal structure evolves from unfilled toward filled tungsten bronze. However, the different doping ion radius causes the differences in occupying initial structural vacancies, resulting in significantly different electrical properties, Li + doping enhances relaxor characteristic whereas Na + and K + doping lead to normal ferroelectric behavior, accompanying an increase in Curie temperature ( T c ) from 36 °C of SBN to 40, 212, 148 °C of Li + , Na + and K + doping, respectively. Benefiting from improved relaxor degree and high density, the Li + doped SBN displays a good energy storage performance. Since the ratio of Sr/Ba and (Sr + Ba)/Nb has not been changed, this work presents direct evidence for the effect of structural vacancy on crystal structure and properties, as well as inspiration for further work on unfilled tungsten bronze.
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Frontiers in Chemistry
·
2023
·
IF 5.5
Gao Bingliang,Liu Zhiwei,Deng Yifan
Al-Li alloy was prepared by electrodeposition on solid aluminum electrode in a urea-LiCl (77.5:22.5, mol%) molten salt system at 353–393 K. The results of cyclic voltammetry and chronopotentiometry show that underpotential deposition of Li occurs on the Al electrode and forms phases of Al(α) and AlLi(δ) which are confirmed by XRD measurements. Scanning electron microscopy observation of deposits indicates that Al-Li alloy with the thickness of 143 µm was obtained by potentiostatic electrolysis at −0.5 V vs. Li+/Li. The Li content in the alloy obtained at 373 K can reach 6.9 wt%. Galvanostatic electrolysis at 20 A demonstrated that Al-Li alloy coating on aluminum plate can be obtained from urea-LiCl electrolyte at 373 K in the atmosphere.
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ACS Sustainable Chemistry & Engineering
·
2023
·
IF 8.4
Fei Fu,Xuan Zhou,Minggui Shen,Dan Wang,Xu Xu,Shibin Shang,Zhanqian Song,Jie Song
With the development of high-frequency communication, the miniaturization of integrated circuits (ICs) has led to interconnected signal delays and losses. The dielectric properties of epoxy resins are no longer satisfactory, because of the presence of polar groups. Herein, a benzocyclobutene-rosin modifier was designed and synthesized to reduce the dielectric constant of epoxy resins. The recross-linking network of benzocyclobutene inhibits the polarizability of the polar groups, and rosin skeletons increase the free volume of epoxy resins. Consequently, the dielectric constant of epoxy resins decreased from 3.12 to 2.72 and their water absorption decreased from 1.06% to 0.861%. The dielectric constant and water absorption are lower than those of most commercial dielectric materials. Additionally, the adhesion of epoxy resins was improved, which broke the contradiction between the dielectric properties and the adhesion of traditional epoxy resins. The modified epoxy resin was finally applied to printed circuit boards. At 15 GHz, its signal loss was 28.8 dB, which was lower than that of a commercial epoxy resin (FR-4), demonstrating that the modified epoxy resin can better meet the miniaturization needs of ICs.
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MACROMOLECULES
·
2019
·
IF 5.997
Chao Qian,Runxin Bei,Tianwen Zhu,Weiwen Zheng,Siwei Liu,Zhenguo Chi,Matthew. P. Aldred,Xudong Chen,Yi Zhang,Jiarui Xu
An original design strategy for the preparation of polymers with a low dielectric constant is presented. The key to this design strategy is taking the most advantage of the secondary relaxation behavior of the polymer chains to obtain more free volume in the bulk, which can effectively reduce the dielectric constant of the polymer. By using this design strategy, we have successfully synthesized a novel polyimide TmBPHF with a pendant group that consists of a biphenyl unit attached to the meta-position of a phenyl ring that is part of a triaryl unit. The intrinsic k and dielectric loss values of the TmBPHF are 2.09 and 0.0012 at 10 kHz, respectively. More importantly, such outstanding low-k performance remains stable up to 300 °C. The excellent low-k performance of TmBPHF is mainly due to the secondary relaxation, especially the β relaxation, which occurs from the rotation of the pendant group. The TmBPHF film shows an ultralow moisture rate (∼0.17%), which is able to maintain the low-k property stability in different humid environments. Meanwhile, the TmBPHF film also shows excellent thermal stability and excellent mechanical properties, with a glass transition temperature (Tg) of 302 °C, 5 wt % decomposition temperature (Td5%) of 549 °C, and residual of 70% at 800 °C under N2. The tensile strength and tensile modulus of the polyimide film are equal to 85.8 MPa and 2.02 GPa, respectively. In addition, the TmBPHF film is soluble in common solvents, which allows simple solution processing and efficient, low-cost, and continuous roll-to-roll processes. The design strategy is beneficial for lowering the k value and simultaneously maintaining the overall properties of polyimides, which possibly could also be extended to other novel high-performance polymer systems.
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CATALYSIS TODAY
·
2017
·
IF 4.636
Zhibiao Shi,Haiyan Yang,Peng Gao,Xiaopeng Li,Liangshu Zhong,Hui Wang,Hongjiang Liu,Wei Wei,Yuhan Sun
A series of TiO 2 supported Co–Cu catalysts with the weight percent of potassium oxides ranged from 0 to 3.5 wt.% were synthesized. This work investigates the influence of potassium promoter on CO 2 hydrogenation to long-chain (C 5+ ) hydrocarbons. The introduction of suitable amount of K into the CoCu/TiO 2 catalyst remarkably promoted the formation of C 5+ hydrocarbons and suppressed methane formation. The temperature-program desorption measurements demonstrate that the addition of K increases the chemisorption of CO 2 , whereas H 2 adsorption is decreased, which enhanced production of liquid fuels. However, these effects were not obvious with the addition of excess amount of K due to the slight change of surface K content. A maximum C 5+ yield with CO 2 conversion of 13% and C 5+ selectivity of 35.1 C-mol% is obtained over the CoCu/TiO 2 catalyst with 2.5 wt.% of potassium promoter loading, which also exhibits a substantial stability.
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JOURNAL OF THE CHINESE CHEMICAL SOCIETY
·
2012
·Vol. 59
·期 11
·1415-1420
·
IF 0.678
Jinyun Peng,Keliang Nong,Lingping Cen
Acid chrome blue K (ACBK) was electropolymerized on the surface of a glassy carbon electrode (GCE) by cyclic voltammetric sweep in the potential range from –0.2 to 0.9 V. The characteristic of poly-ACBK film was studied by different methods such as electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. This modified electrode showed excellent electrocatalytic response to curcumin with the increase of the electrochemical responses. Under the optimal conditions a good linear voltammetric response could be obtained over the range of 1.0 × 10 −7 -7.0 × 10 −5 M and the detection limit was got as 4.1 × 10 −8 M (S/N = 3). The method was successfully applied for the determination of curcumin in human urinev samples.
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TALANTA
·
2015
·
IF 3.545
Shenguang Ge,Lina Zhang,Yan Zhang,Haiyun Liu,Jiadong Huang,Mei Yan,Jinghua Yu
A low-cost, simple, portable and sensitive paper-based electrochemical sensor was established for the detection of K-562 cell in point-of-care testing. The hybrid material of 3D Au nanoparticles/graphene (3D Au NPs/GN) with high specific surface area and ionic liquid (IL) with widened electrochemical windows improved the good biocompatibility and high conductivity was modified on paper working electrode (PWE) by the classic assembly method and then employed as the sensing surface. IL could not only enhance the electron transfer ability but also provide sensing recognition interface for the conjugation of Con A with cells, with the cell capture efficiency and the sensitivity of biosensor strengthened simultaneously. Concanavalin A (Con A) immobilization matrix was used to capture cells. As proof-of-concept, the paper-based electrochemical sensor for the detection of K-562 cells was developed. With such sandwich-type assay format, K-562 cells as model cells were captured on the surface of Con A/IL/3D AuNPs@GN/PWE. Con A-labeled dendritic PdAg NPs were captured on the surface of K-562 cells. Such dendritic PdAg NPs worked as catalysts promoting the oxidation of thionine (TH) by H 2 O 2 which was released from K-562 cells via the stimulation of phorbol 12-myristate-13-acetate (PMA). Therefore, the current signal response was dependent on the amount of PdAg NPs and the concentration of H 2 O 2 , the latter of which corresponded with the releasing amount from cells. So, the detection method of K-562 cell was also developed. Under optimized experimental conditions, 1.5×10 −14 mol of H 2 O 2 releasing from each cell was calculated. The linear range and the detection limit for K-562 cells were determined to be 1.0×10 3 –5.0×10 6 cells/mL and 200 cells/mL, respectively. Such as-prepared sensor showed excellent analytical performance with good fabrication reproducibility, acceptable precision and satisfied accuracy, providing a novel protocol in point-of-care testing of cells.
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JOURNAL OF CHEMICAL THERMODYNAMICS
·
2016
·
IF 2.196
Hengde Li,Zhangni Feng,Li Wan,Cheng Huang,Tianfei Zhang,Yanxiong Fang
As an eco-friendly compound from essential oils, 1,8-cineole (cineole, eucalyptol) has the potential to replace the ozone depleting industrial solvents. This paper presents experimental (liquid + liquid) equilibrium (LLE) data for four alcohol–water systems containing 1,8-cineole. To evaluate the phase equilibrium properties of 1,8-cineole in aqueous alcohol mixtures, LLE values for the ternary systems (water + methanol or ethanol or 1-propanol or 1-butanol + 1,8-cineole) were determined with a tie-line method at T = 298.15 K under atmospheric pressure. The well-known Hand, Bachman and Othmer–Tobias equations were used to test the reliability of the experimental results. The binodal curves and distribution ratios of alcohol in the mixtures are shown and discussed. The experimental LLE values were satisfactorily correlated by the NRTL and UNIQUAC models.
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JOURNAL OF MOLECULAR LIQUIDS
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2012
·
IF 1.58
Mengyin Hou,Yingjie Xu,Yajuan Han,Bin Chen,Wenxia Zhang,Qinghua Ye,Jinzhi Sun
Densities ( ρ ), refractive indices ( n D ) and electrical conductivities ( κ ) of ethylammonium acetate (N2Ac) protic ionic liquid + water and propylammonium acetate (N3Ac) protic ionic liquid + water binary mixtures over the entire composition range were measured at 298.15 K under atmospheric pressure. The excess molar volumes ( V E ), apparent molar volumes ( V ϕi ), partial molar volumes ( V ¯ m , i ) and excess partial molar volumes ( V ¯ m , i E ) of the binary mixtures were calculated from the density data. The refractive index deviations (Δ n D ) of the binary mixtures were determined using the refractive index data. The excess molar volumes and refractive index deviations were correlated with the Redlich–Kister equation. The excess molar volumes of the above-mentioned systems are negative over the whole composition range, while the refractive index deviations are positive. The concentration dependence of electrical conductivity was fitted according to the empirical Casteel–Amis equation. The intermolecular interactions and structural effects were analyzed on the basis of the measured and the derived properties.
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