DRYING TECHNOLOGY
·
2020
·
IF 2.988
Wei Wang,Shuo Zhang,Yanqiu Pan,Yujia Tang,Guohua Chen
To explore the effect of wave-absorbing material aided microwave heating on freeze-drying of initially porous frozen material, a lab-scale microwave freeze-dryer was designed with solid-state source selected as the microwave source instead of the traditionally used magnetron. Vitamin C was employed as the solute in aqueous solution. “Soft-ice” freezing technique was adopted to prepare solid and porous frozen materials. Experimental results showed that the solid sample by soft-ice freezing can successfully avoid structural collapse during freeze-drying, and the porous frozen material can significantly intensify mass transfer of the freeze-drying process. Under the operating conditions of 35 °C and 20 Pa, the drying time of the porous sample with the initial saturation of 0.25 decreased by 30.4% compared with the solid one, and the residual moisture content of dried product decreased with the initial saturation reducing. SEM images of the dried products revealed that the porous material had a loose pore structure and a tenuous solid skeleton, which is favorable to the migration of sublimated/desorbed vapor and the desorption of bound moisture. Evidences also showed that appropriately increasing radiation temperature led to reducing the drying time, while changing chamber pressure had an insignificant effect on freeze-drying. With sintered silicon carbide (SiC), which is a kind of wave-absorbing material, as the supporting pad of sample, microwave heating can greatly improve heat transfer of the freeze-drying process. Under the same operating conditions, the drying time of the porous sample with the microwave input power of 5 W was 28.1% shorter than that of the same sample without microwave heating, and 50.0% shorter than that of the solid sample for conventional freeze-drying. Wave-absorbing material aided microwave freeze-drying of the porous material frozen with preformed pores is a feasible and effective way to achieve the simultaneous intensification of heat and mass transfer in freeze-drying.
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DOI
高影响因子
Materials Today Chemistry
·
2021
·
IF 8.301
Y. Ji,W. Luo,Y. Liu,Z. He,N. Cheng,Z. Zhang,X. Qi,J. Zhong,L. Ren
The bottleneck of alkaline hydrogen evolution reaction lies in the kinetically sluggish brought from multistep reaction processes involving water adsorption and dissociation, as well as hydrogen adsorption. In this work, we successfully synthesized o-CoSe 2 /c-CoSe 2 heterostructures anchored on MoSe 2 nanosheets to powerfully promote reaction processes. As an electrocatalyst , it exhibits a low overpotential of 112 mV at 10 mA/cm 2 and a Tafel slope of 96.9 mV/dec for an alkaline hydrogen evolution reaction . Moreover, the as-prepared catalyst can behave as both cathode and anode for overall water splitting , which only requires 1.61 V cell voltage at 10 mA/cm 2 . Significantly, the cell voltage can be further reduced to 1.53 V at 10 mA/cm 2 for water electrolysis under the simulated solar irradiation owing to such a semiconductor-based heterostructure that facilitates the separation of photogenerated charges. Here, the improving overall performance of this ternary electrocatalyst is attributed to the multifunctionality and synergistic interaction of different components in this heterogeneous material . The work provides a novel strategy to design active catalysts simultaneously using electric energy and solar energy for effective water splitting.
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DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2022
·Vol. 46
·期 37
·18069-18075
·
IF 3.925
Qianqian Li,Man Zhang,Yutong Nong,Qichang Pan,Youguo Huang,Hongqiang Wang,Fenghua Zheng,Qingyu Li
Zinc sulfide (ZnS) is considered as a candidate anode material to replace commercial graphite anodes in high-performance lithium-ion batteries (LIBs). However, the significant volume change during the lithiation/delithiation process leads to poor cycle and rate performance, severely limiting the application of the ZnS anode in LIBs. Here, core–shell ZnS@C microrods (ZnS@C MRs) were synthesized via a simple hydrothermal method, followed by in situ polymerization and a sulfidation process. Due to the rationally designed structure, the outer carbon shell can avoid the volume expansion of ZnS, thus maintaining the structural stability. Moreover, the carbon shell can not only enhance the conductivity, but also inhibit direct contact between ZnS and the electrolyte during the repeated lithiation/delithiation process. Accordingly, ZnS@C MRs exhibit outstanding electrochemical performance in LIBs. Specifically, a capacity of 392 mA h g−1 is obtained after 500 cycles at 1.0 A g−1. Moreover, a capacity of 162 mA h g−1 is maintained at 3.0 A g−1.
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DOI
高影响因子
NANOTECHNOLOGY
·
2019
·Vol. 30
·期 30
·305402
·
IF 3.399
Tong Wu,Yaying Li,Yuntong Li,Jing Hong,Haiyang Wu,Jie Mao,Yuzhe Wu,Qipeng Cai,Conghui Yuan,Lizong Dai
Simultaneous introduction of both transition metal and other inorganic elements into the carbon matrix has attracted great attention in the fabrication of carbon materials with high electrochemical properties. Herein, rational design of ligand-iron coordinative supramolecular precursors is achieved for the fabrication of Fe-N/C catalysts, which possess high oxygen reduction reaction (ORR) performance. A series of precursors are prepared by a simple coordination reaction between a three armed catechol monomer and iron ions. Particular interest is focused on tuning the doping species, surface area and morphology of the Fe-N/C catalysts through a simple selection of iron resources. We show that an Fe-N/C catalyst derived from Fe2(SO4)3 at a carbonization temperature of 800 °C, has the optimized ORR performance with an onset potential of 0.930 V and half-wave potential of 0.801 V. Detailed investigation indicates that the synergistic effect among doping elements of nitrogen and sulfur and the unique carbon structure determines the performance of the Fe-N/C catalysts. Our findings may be of significance for the fabrication of doped carbon materials using coordinative supramolecular polymers as precursors.
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DOI
高影响因子
FITOTERAPIA
·
2019
·
IF 2.431
Xue Li,Ling-Juan Zhu,Jin-Peng Chen,Chen-Yu Shi,Li-Ting Niu,Xue Zhang,Xin-Sheng Yao
One new flavanonol , demethylmatteucinol ( 1 ), and nine new flavanone glucoside derivatives, matteflavosides H-J ( 2–4 ) and matteuinterates A-F ( 5 – 10 ), were isolated from the rhizomes of Matteuccia intermedia C.Chr., along with 21 known flavanones ( 11 − 31 ). Notably, all of them contain C -methylation in the A-ring. The structures of the compounds were elucidated by spectroscopic methods and chemical derivatization. The α -glycosidase inhibition assay indicated that compounds 12 – 17 showed potent inhibitory activity with IC 50 values of 12.4–69.7 μM, which suggested their hypoglycemic effect.
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DOI
高影响因子
Frontiers of Materials Science
·
2025
·Vol. 19
·期 1
·1-13
·
IF 2.3
Zhao Jingkun,Yao Shuaikang,Huang Yingjie,Gao Siyu,Zhai Shangru,An Qingda,Xiao Zuoyi,Zhang Feng
It is undoubtedly a challenge to design an efficient and recyclable photocatalyst for the degradation of tetracycline (TC). In this study, a MoS 2 @C composite catalyst was fabricated through the simple sulfurization of alginate-based spheres encapsulating ammonium molybdate by thiourea. The incorporation of porous carbon as a co-catalyst significantly augmented reactive active sites, endowing it with great specific surface area and effectively preventing the aggregation of MoS 2 nanoparticles. While offering abundant catalytic sites for the reaction, the structure with interconnected channels promoted the adsorption of the reactant. The MoS 2 @C composites showed excellent photocatalytic performance, achieving a photodegradation ratio of 87.01% for TC within 60 min, superior to that of pure MoS 2 . Additionally, the photocatalytic mechanism for the degradation of TC was also investigated through free radical trapping experiments in combination with the electron spin resonance technique.
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高影响因子
CRYSTENGCOMM
·
2019
·Vol. 21
·期 40
·6010-6017
·
IF 3.382
Shuai Fang,Hongan Ma,Zhanke Wang,Zhiqiang Yang,Zheng-hao Cai,Luyao Ding,Xinyuan Miao,Liangchao Chen,XiaoPeng Jia
FeS is the main sulfur-containing compound in natural diamond inclusions. The research on FeS-doped diamond crystals plays an extremely important role in exploring the growth environment of natural diamond and the chemical composition of the earth. In our work, the characteristics of FeS doped diamond crystals were studied by using a China-type large volume cubic high-pressure apparatus with an iron–nickel alloy as a catalyst at 6.0 GPa and 1300–1350 °C. The crystals were characterized by OM, SEM, XPS, FTIR and Raman. Scanning electron microscopy of the crystal shows that the {100} plane of the crystal is rougher than {111}, which is related to the number of dangling bonds on different crystal faces of the crystal. The residue on the surface of the crystal was detected by mapping, and the test result showed that it was a sulfur iron and a sulfur nickel compound. FeS will decompose in the synthesis system, and the decomposition products are Fe and S2.The XPS spectrum of the crystal shows that S was successfully incorporated into the diamond lattice by forming C–S–O and C–S–SO2–C bonds, and the peak intensity was strong. The infrared spectrum shows that the N content in the crystal gradually increases as the doping ratio increases. Raman spectroscopy analysis shows that the S-doped Ib-type diamond single crystal has a high-quality sp3 structure, and the full width at half maximum (FWHM) of the crystal gradually broadens as the doping ratio increases.
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高影响因子
Nano-Micro Letters
·
2021
·Vol. 14
·期 1
·1-12
·
IF 16.419
Zhu Mengya,Li Guangyong,Gong Wenbin,Yan Lifeng,Zhang Xuetong
A calcium-doped boron nitride (Ca-BN) aerogel was synthesized by introducing Ca into crystal structure of BN building blocks.
The aerogels exhibited superior high-temperature stability and could resist the burning of butane flame (~1300 °C) in air atmosphere.
Ca-BN aerogel, together with Al foil, can effectively hide thermal target at high temperature up to 1300 °C.
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高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2019
·Vol. 55
·期 8
·3495-3506
·
IF 3.442
Zhao Chenhao,Shen Zhen,Tu Fengzhang,Hu Zhibiao
Transition metal selenides nanoparticles/carbon composites have been one of the promising lithium/sodium ion battery anodes. In the present study, NiSe x nanoparticles encapsulated into microporous flowerlike carbon have been prepared by a hydrothermal route directed by the flowerlike Ni/C composite template. In a low hydrothermal temperature (i.e., 120 °C), the metallic Ni nanoparticles are transformed into Ni 0.85 Se, which has an average particle size of ~ 13.02 nm. The selenization degree and particle size can be obviously improved at a higher hydrothermal temperature (i.e., 160 or 180 °C), accompanying with the decrease in carbon content, and partial Ni 0.85 Se nanoparticles have been transformed into NiSe 2 . As anode of lithium ion batteries, the NiSe x obtained at 180 °C (i.e., 180 °C-NiSe) can deliver a higher discharge capacity (e.g., 851.0 mA h g −1 after 100 cycles at 0.2 A g −1 ) and better cycling stability compared with the low temperature obtained sample. However, the rate capability and sodium ion storage performance of 120 °C-Ni 0.85 Se are better than the 180 °C-NiSe x , and a discharge capacity of 326.5 mA h g −1 can be reached at a high rate of 5 A g −1 for 120 °C-Ni 0.85 Se. Also, a high capacity retention ratio of 64.3% after 100 cycles can be reached for 120 °C-Ni 0.85 Se as sodium ion battery anode. The different electrochemical performance can be attributed to the decreased particle size.
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高影响因子
Journal of Materials Chemistry A
·
2020
·Vol. 8
·期 15
·7145-7157
·
IF 11.301
Jinling Xue,Yinshi Li,Jue Hu
It remains a major challenge to develop a facile method to prepare non-noble metal electrocatalysts with high activity and durability to drive the sluggish oxygen reduction reaction (ORR) for proton exchange membrane fuel cells (PEMFCs). Herein, a highly efficient bimetallic Zn/Fe@N-doped hierarchical porous carbon (Zn/Fe–N–C) catalyst derived from ZIF-8 and hemin (host–guest) was firstly reported by one-step thermal treatment. Fe2+ spatially separated by using the hemin guest in the ZIF-8 framework and hydrocarbon-branched chains form rich Fe–Nx active sites, and the evaporation of Zn2+ generates a highly porous structure in the Zn/Fe–N–C catalysts. Benefitting from this unique structure and composition, the resulting Zn/Fe2–N–C catalyst exhibits excellent ORR activities in both 0.1 M KOH (onset potential, Eonset = 1.08 V, and half-wave potential, E1/2 = 0.86 V vs. RHE) and 0.5 M H2SO4 media (Eonset = 1.04 V and E1/2 = 0.81 V), which are even comparable to those of the commercial Pt/C catalyst, and ranks among the top reported electrocatalysts. In addition, it also has outstanding long-term durability and good methanol resistance, much better than those of Pt/C in both acidic and alkaline media, which makes it one of the best non-noble alternatives of Pt-based catalysts for ORR electrocatalysis. This work highlights the potential to rationally design and fabricate high-performance ORR catalysts for fuel cell applications.
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高影响因子
ELECTROCHIMICA ACTA
·
2020
·
IF 6.215
Pengcheng Zhang,Yi Feng,Mengjue Cao,Jianfeng Yao
Co 9 S 8 nanoparticles (NPs) anchored on carbonized melamine foam with polydopamine derived carbon coating (CMF-Co 9 S 8 -C) was successfully constructed for advanced lithium-ion battery anode. The sandwich-type structure consists of massive Co 9 S 8 NPs and dual N-doped carbon layers that not only accommodate the volume expansion effect but also shortens the transfer distance of Li + / e − . Moreover, the nanocomposite inherits 3D carbon network with hierarchical porous structure, which is beneficial for providing sufficient transport channels and contacting with electrolyte. With the prominent synergistic effects from structure and chemical properties, CMF-Co 9 S 8 -C hybrid compound exhibited high specific capacity of 645 mAh g − 1 at 0.5 A g − 1 after 200 cycles, and it delivered excellent cycling stability (520 mAh g − 1 ) under a high current (2 A g − 1 ) after 1000 cycles.
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DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2022
·
IF 6.371
Hua Ma,Xiuwen Wu,Xiuli Fu,Zhijian Peng
The development of a facile strategy to fabricate inexpensive and efficient nonnoble metal-based alloys to replace their traditionally costly noble-metal counterparts for electrocatalytic water splitting holds great appeal. Here, we report novel FeNi-FeCo-C composite nanofibers (FeNi-FeCo-C CNFs), which was prepared simply by electrospinning a precursor solution containing Fe, Ni and Co nitrates together with polyacrylonitrile powders and subsequent thermal treatment. The optimal FeNi-FeCo-C CNFs prepared with 10 wt% polyacrylonitrile at a thermal treatment temperature of 800 °C show excellent electrocatalytic performance for oxygen evolution in a 1 mol·L −1 KOH aqueous solution with a relatively small overpotential of 262 mV at 10 mA cm −2 , a low Tafel slope of 47.2 mV dec −1 , and excellent cycling stability. The present strategy will provide new insight for the design and fabrication of electrocatalysts for water splitting.
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高影响因子
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