POLYMERS FOR ADVANCED TECHNOLOGIES
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2021
·Vol. 32
·期 11
·4450-4463
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IF 3.665
Kexin Chen,Dong Yang,Yongqian Shi,Yuezhan Feng,Libi Fu,Chuan Liu,Ming Chen,Fuqiang Yang
The design of high-performance compounded flame retardants based on multielement can be of great significance for reducing the flammability of polymer materials. In this article, a new type of N-P-Cu containing supermolecular assembly network (MPCSN) flame retardant was prepared and subsequently added into thermoplastic polyurethane elastomer (TPU)/silicon microencapsulated ammonium polyphosphate (SiAPP) composites. The obtained results indicated that a series of TPU/SiAPP/MPCSN composites exhibited strong adhesions with the TPU matrix. Additionally, the thermal and flame retardant performances of TPU composites were markedly improved after the introduction of different proportions of SiAPP to MPCSN. For example, the peak of heat release rate, the total heat release, the peak of smoke production rate, the total smoke release of the TPU composite containing 7.5 wt% SiAPP and 2.5 wt% MPCSN (TPU/SiAPP3/MPCSN1) remarkably decreased by 68.7%, 52.9%, 52.4%, and 49.4%, respectively, besides the highest LOI value (27.5 vol%) and UL-94 V-0 rating, compared with those of pure TPU. The improved flame retardance of the TPU/SiAPP3/MPCSN1 composite was due to the explanations: On one hand, a compact intumescent char effectively protected the TPU matrix from heat and oxygen and retarded the gaseous products permeation into the combustion zone; on the other hand, evolved phosphorus-containing free radicals captured the H• and HO• generated from the TPU material. The synergistic effect of SiAPP and MPCSN resulted in strong flame suppression, accompanied by 10.8% and 37.8% reductions in FIGRA and Av-EHC, respectively. This article offers a facile approach to fabricate highly effective flame-retardant TPU composites.
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ADVANCED FUNCTIONAL MATERIALS
·
2021
·Vol. 31
·期 30
·2102768
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IF 18.808
Huan Wei,Ping-An Chen,Jing Guo,Yu Liu,Xincan Qiu,Huajie Chen,Zebing Zeng,Thuc-Quyen Nguyen,Yuanyuan Hu
Doping is a powerful technique for tuning the electrical properties of organic semiconductors (OSCs). Although numerous studies are performed on OSC doping, thus far only a few n-type dopants have been developed. Herein, two low-cost nucleophilic organic bases are reported, namely 1,5,7-Triazabicyclo [4.4.0] dec-5-ene (TBD) and 1,5-Diazabicyclo [4.3.0] non-5-ene (DBN) for n-doping of OSCs. The two dopants are found to significantly enhance the electrical conductivity of OSCs. In particular, compared to the classic n-dopant 4-(2,3-Dihydro-1,3-dimethyl-1 H -benzimidazol-2-yl)- N , N -dimethylbenzylamine ( N -DMBI), DBN results in significantly higher conductivity and also lower activation energy in N2200 films, indicating its high doping performance. The utilization of the n-dopants for improving device performance and controlling the device polarity of organic field-effect transistors are demonstrated. Furthermore, these dopants are employed for fabricating organic thermoelectric devices, and the power factor value of DBN-doped N2200 films is found to be about 1.6 times higher than that of N -DMBI-doped films. These results show the feasibility of using low-cost organic bases as efficient n-dopants and demonstrate their promising applications in organic electronics.
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FUEL
·
2021
·
IF 6.609
Zhanjun Cheng,Wenhao Yin,Jing Tian,Wei He,Jinglan Wang,Jiuzhong Yang,Lili Xing,Beibei Yan,Guanyi Chen
The pyrolysis of di- n -propyl ether (DPE), a potential biofuel candidate, was studied under a temperature range of 850–1350 K in a flow reactor at low and atmospheric pressures. Synchrotron vacuum ultraviolet photoionization mass spectrometry was used for isomeric identification and mole fraction measurements of the pyrolysis products, especially the free radicals. Specific products were observed and measured for the unimolecular decomposition reactions of DPE. A detailed kinetic model of DPE pyrolysis was developed based on the n -propanol combustion model. Modeling analyses including the rate of production (ROP) and sensitivity analyses were performed to reveal the consumption pathways of DPE, as well as the formation and consumption pathways of intermediates and products. ROP and sensitivity analyses indicated that the consumption reaction of DPE was mainly controlled by the unimolecular decomposition reactions and H-abstractions at both low and atmospheric pressures. The pericyclic reaction, leading to n -propanol + propylene, was the most important unimolecular decomposition reactions, especially at low pressure. The H-abstraction reactions of DPE played crucial roles in its consumption. Further β -C–C and β -C–O scission reactions of the three primary radicals can produce some oxygenated and hydrocarbon products. Relatively high mole fractions of C1–C3 aldehydes and C1–C3 alkane, alkene, and alkyl radicals were observed, which demonstrated the structural feature of DPE. Comparison of the product distribution between DPE and n -propanol were also analyzed.
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MICROPOROUS AND MESOPOROUS MATERIALS
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2021
·
IF 5.455
Junfeng Miao,Xiaoxi Dong,Shasha Wang,Yuelong Xu,Zuozhao Zhai,Lihui Zhang,Bin Ren,Zhenfa Liu
The preparation method of porous carbon traditionally involves many steps and requires inert atmosphere resulting in time-consuming and high-cost. We reported a simple and easy method of N-doped micro/meso porous carbon (NPC) via a one-step carbonization of polyvinylpyrrolidone, melamine and ammonium chloride in air. The influences of PVP mass and carbonization temperature on surface group function, the morphology, microstructure and pore distribution of NPC samples were studied by Fourier transform infrared spectroscopy , X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy , X-ray diffraction, Raman spectroscopy and surface area analysis. The thermal behavior of NPC was analyzed by thermogravimetric analysis coupled to Fourier transform infrared spectroscopy. Moreover, the electrochemical performances of the as-prepared NPC samples were measured by cyclic voltammetry , galvanostatic charge-discharge and electrochemical impedance spectroscopy . The micro/meso pores and high content of pyridine-N and quaternary-N endowed NPC samples with high capacitive performance and long cyclic life. The specific capacitance of the prepared NPC sample could reach as high as 215.9 F g −1 at 1 A g −1 and 89.5 F g −1 even at 10 A g −1 . Especially, the symmetric supercapacitor assembled by NPC-3-900 achieved 13.2 W h kg −1 at 350 W kg −1 and excellent cyclic performance (91.4% after 10,000 GCD circles).
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2021
·
IF 5.816
Guilin Li,Lei Li,Zhan Lin
Electrocatalytic water splitting, as an ideal technology in renewable energy applications , suffers from high electrical energy consumption due to the slow kinetics of HER and OER reactions. Therefore, it is urgent to design efficient bifunctional catalysts to improve the reaction kinetics. Herein, a self-supported electrode, anchoring CoP nanoparticles on N-doped carbon/graphene (NC-G) and chemically growing on Ni foam as a whole electrode (denoted as NC-G-CoP/NF) displays promising electrocatalytic performance in 1.0 M KOH electrolyte, with a low overpotentials of 68 mV at 10 mA cm −2 for HER and 255 mV at 50 mA cm −2 for OER. This bifunctional electrocatalyst only needs 1.435 V to generate 10 mA cm −2 for overall water splitting. The outstanding electrocatalytic performance is ascribed to the following factors: i) inherent nature of transition metal phosphides, ii) abundant and high dispersion N active sites in NC-G, iii) strong interaction between the NC-G and CoP nanoparticles, and iv) rapid electron transfer between the catalytic centers and Nickle foam. This provides a new perspective to design efficient electrocatalysts for electrocatalytic water splitting.
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BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
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2021
·
IF 3.575
Dandan Zheng,Jinglong Wang,Genju Li,Lulu An,Ying Qu,Qinxiu Zhang,Wenhui Ye,Xin Zhao,Zhongxi Zhao
Autophagy-impairment is involved in the pathological process of chronic obstructive pulmonary disease (COPD), and relates to inflammation and emphysema in lung injury. This study aimed to elucidate the protective effect of S -Allylmercapto- N -acetylcysteine (ASSNAC) against COPD via regulating the autophagy. Firstly, porcine pancreatic elastase (PPE)-induced COPD model in A549 cells was established, and ASSNAC was verified to alleviate the autophagy-impairment from the results of western blotting analysis of LC3BⅡ/Ⅰ and monodansylcadaverine (MDC) staining of autophagosome . Secondly, Balb/c mice were stimulated by PPE to induce the COPD model in vivo . The histological analysis of lung tissues presented that ASSNAC could alleviate the lung injury induced by PPE. Thirdly, the secretions of NO , TNF- α and IL-1 β in serum and BALF were reduced by ASSNAC compared with the PPE group. Finally, the mechanism of therapeutic effects of ASSNAC against COPD through regulating the autophagy-impairment was clarified. That is, ASSNAC inhibits the phosphorylation of PI3K/Akt/mTOR signaling pathways. In a word, this research provides a reference for ASSNAC to be an effective drug for pulmonary diseases.
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PubMed
高影响因子
ENVIRONMENTAL POLLUTION
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2021
·
IF 8.071
Shengyong Lu,Xinlei Huang,Minghui Tang,Yaqi Peng,Shuchao Wang,Chengetai Portia Makwarimba
Typical organic pollutants from coal-combustion flue gas such as volatile organic compounds (VOCs) need to be effectively controlled. This work synthesized a series of nitrogen-doped hierarchical porous carbons (NHPCs) by one-step activation with various proportions of cellulose, (NH 4 ) 2 C 2 O 4 and KHCO 3 /NaHCO 3 . The NHPCs have a high specific surface area and pore volume up to 2816 m 2 /g and 1.413 cm 3 /g as well as a hierarchical porous structure with micro-meso-macropores distribution. The dynamic adsorption tests of toluene at 600 ppm showed that NHPCs have a high adsorption capacity up to 585 mg/g (NHPC(K)131), this was about 3 times more than that of AC (208 mg/g), and is a better absorbent compared to many other carbon adsorbents. The porous characteristics and toluene adsorption properties of NHPCs improved along with the fluctuation of the proportions of raw materials and active agents. The micropore size of the material is the main factor that affecting the toluene adsorption capacity. The analysis of toluene dynamic adsorption breakthrough curves revealed that NHPCs had great toluene adsorption kinetics with high adsorption rate constants and short mass transfer zone. The excellent toluene adsorption kinetics of NHPCs can be attributed to the hierarchical porous structure. The abundant 2–10 nm mesopores and macropores of NHPCs act as mass transfer channels for toluene molecules. The XPS analysis showed that the NHPCs have nitrogen doping up to 6.71% (NHPC(Na)161) and they effectively promote toluene adsorption. The nitrogen doping mechanism can be attributed to the reactions between cellulose pyrolysis substances and NH 3 which decomposed from (NH 4 ) 2 C 2 O 4 . Moreover, the pore forming reactivity of KHCO 3 is better than that of NaHCO 3 in the NHPCs activation process.
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ACS Applied Materials & Interfaces
·
2021
·
IF 9.229
Xiaona Chen,Linan Feng,Penglu Yu,Chan Liu,Jinle Lan,Yuan-Hua Lin,Xiaoping Yang
Flexible thermoelectric materials and devices have gained wide attention due to their capability to stably and directly convert body heat or industrial waste heat into electric energy. Many research and synthetic methods of flexible high-performance p-type thermoelectric materials have made great progress. However, their counterpart flexible n-type organic thermoelectric materials are seldom studied due to the complex synthesis of conductive polymer and poor stability of n-type materials. In this work, bismuth tellurium (Bi2Te3) nanosheets are in situ grown on single-walled carbon nanotubes (SWCNTs) assisted by poly(vinylpyrrolidone) (PVP). A series of flexible SWCNTs@Bi2Te3 composite films on poly(vinylidene fluoride) (PVDF) membranes are obtained by vacuum-assisted filtration. The high electrical conductivity of 253.9 S/cm, and a corresponding power factor (PF) of 57.8 μW/m·K2 is obtained at 386 K for SWCNTs@Bi2Te3-0.8 film. Moreover, high electrical conductivity retention of 90% can be maintained after a 300-cycle bending test and no obvious attenuation can be detected after being stored in an Ar atmosphere for 9 months, which exhibits good flexibility and excellent stability of the SWCNTs@Bi2Te3 composite films. This work shows a convenient method to fabricate n-type and flexible thermoelectric composite film and further promotes the practical application of n-type flexible thermoelectric materials.
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高影响因子
ACS Applied Energy Materials
·
2021
·
IF 6.024
Zhi Xu,Le Li,Xiaoxia Chen,Guyu Xiao
The fabrication of high-performance metal-free carbon catalysts for the oxygen reduction reaction (ORR) is of practical importance for the energy sector. A novel fabrication strategy was used to prepare high-performance N,S-codoped mesoporous carbons (NSMPCs) as ORR catalysts, involving the preparation of poly(3-aminothiophenol)-based assemblies followed by subsequent pyrolysis. The N and S heteroatoms of the poly(3-aminothiophenol) are incorporated into the NSMPCs by pyrolysis, forming abundant catalytic active sites. The mesopores of NSMPCs locate on their surface, which are derived from the degradation of the micelle templates. These shallow mesopores greatly enhance the specific surface area and promote the mass transfer for the ORR. Moreover, the embedded graphene (or carbon nanotube) in the NSMPCs facilitates electron transport during the ORR. These factors are synergistically modulated to boost the catalytic performances of NSMPCs. As a result, NSMPCs exhibit superb catalytic performances, close to or better than those of the best performing metal-free carbon ORR catalysts reported to date and commercial Pt/C in alkaline electrolyte. This synergistic strategy provides a facile pathway for the fabrication of advanced metal-free carbon ORR catalysts.
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高影响因子
FLUID PHASE EQUILIBRIA
·
2021
·
IF 2.775
Junwei Cui,Jiangtao Wu,Shengshan Bi
Systems in connection with hydrocarbons with dissolved carbon dioxide (CO 2 ) are widespread in various chemical and engineering applications such as Fischer–Tropsch (FT) synthesizes, carbon capture and storage (CCS) and enhanced oil recovery (EOR). The thermophysical properties are necessary for understanding and designing those relevant processes. In this work, the liquid viscosity, interfacial tension, thermal diffusivity and mutual diffusivity of n -tetradecane with dissolved CO 2 were investigated under macroscopic equilibrium from 323 to 473 K and over a pressure range up to 5.6 MPa. With a careful evaluation of the uncertainty, the average expanded uncertainty of liquid viscosity, surface tension, thermal diffusivity and mutual diffusivity was 2.9%, 2.4%, 11.4% and 4.4%, respectively. The liquid viscosity and interfacial tension decline when the pressure of the system or the mole fraction of CO 2 in the liquid phase increases. Empirical correlations were used to represent the liquid viscosity and interfacial tension with an absolute average deviation (AAD) of 2.8% and 0.2 mN · m − 1 . A comparison of available liquid viscosity and interfacial tension from the literature were performed. In the overlapped temperature and pressure region, good agreement can be found. In terms of the thermal diffusivity, there is no obvious dependency on pressure. The mutual diffusivity decreases with pressure at 323 K, while the decline behavior cannot be observed above 323 K when taking the combined uncertainty into consideration. This work was expected to provide reliable and accurate fundamental thermophysical properties of liquid with dissolved gas systems in engineering and chemical processes.
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RSC Advances
·
2021
·Vol. 11
·期 6
·3770-3776
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IF 3.361
Guangtao Qian,Fengna Dai,Haiquan Chen,Mengxia Wang,Mengjie Hu,Chunhai Chen,Youhai Yu
5-Amine-2-(4-amino-benzene)-1-phenyl-benzimidazole (N-PhPABZ) was successfully synthesized and polymerized with 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA) to obtain a novel N-phenyl-poly(benzimidazole imide) (N-Ph-PBII). The successful incorporation of N-phenyl addressed the issue of high H2O-absorption of traditional PBIIs while retained the superheat resistance property. The resulting N-Ph-PBII possessed a high glass-transition temperature (Tg) up to 425 °C and a low affinity for water of 1.4%. Furthermore, the loose molecular packing and noncoplanar structures led to an increase in optical transparency for the modified PBII.
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高影响因子
Catalysis Science & Technology
·
2021
·Vol. 11
·期 6
·2327-2339
·
IF 6.119
Xianliang Qiao,Xinyu Liu,Zhiqiang Zhou,Qingxin Guan,Wei Li
Mercury chloride is a key catalyst for acetylene hydrochlorination to produce vinyl chloride, which is the main raw material for the manufacture of PVC. However, the extensive use of mercury has caused serious environmental problems. Herein, a green poly(o-phenylenediamine) framework was synthesized for acetylene hydrochlorination. The polymer is composed of a phenazine backbone with defined pyridinic N species, which is an ideal model system for the study of the catalytic role of pyridinic N in the reaction. The polymer has bifunctional properties. When acting as a polymer catalyst, it achieved ≈95% conversion of acetylene at 280 °C and exhibited a satisfying stability during a 100 h continuous test. Active sites and reaction paths on the pyridinic N structure were well explored through catalytic experiments, spectroscopic characterizations, and density functional theory calculations. As an important extension of its application, the polymer was then used as a suitable precursor to prepare an N-doped carbon catalyst. The polymer-derived carbon catalyst exhibited surprising acetylene hydrochlorination activity, which was comparable to that of a 6 wt% Hg/C catalyst. This work proposes a new strategy for constructing highly efficient mercury-free catalysts with target active species and will contribute to the sustainable development of the PVC industry.
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