ChemElectroChem
·
2019
·Vol. 6
·期 15
·3920-3927
·
IF 3.975
Yang Yang,Min Zhao,Jian Xiong,Hongbo Geng,Yufei Zhang,Cheng Chao Li,Jinbao Zhao
Graphical Peas in a pod : Cowpea-like Li 3 VO 4 @C nanowires are prepared through a simple electrospinning method. In this special structure, Li 3 VO 4 nanoparticles are uniformly encapsulated in the carbon nanofibers just like peas in their pods. Benefiting from the characteristic 1D nanowire morphology and uniform carbon coating layer that greatly enhances the electronic conductivity as well as shortens the transport pathways of Li + ions, the cowpea-like Li 3 VO 4 @C exhibits excellent cycling stability and remarkable rate performance. Owing to the high theoretical capacity (394 mAh g −1 ) and appropriate lithiation voltage (0.5–1.0 V vs Li + /Li), Li 3 VO 4 is highly regarded as an attractive anode candidate for high-safety lithium-ion batteries. However, its high-rate performance is seriously restricted by the sluggish electrode kinetics. To address these problems, we synthesize cowpea-like Li 3 VO 4 @C nanowires through a facile electrospinning method. In this well-designed structure, Li 3 VO 4 nanocrystals are uniformly encapsulated in conductive carbon nanofibers just like peas in their pods. The 1D morphology with high electronic conductivity can afford high Li + ions diffusion rate and fast surface charge storage mechanism, leading to significantly enhanced electrochemical kinetics. Even after 1000 cycles at 2 A g −1 , the reversible capacity of cowpea-like Li 3 VO 4 @C nanowires can be maintained at 318.0 mAh g −1 without obvious capacity decay.
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BIOTECHNOLOGY PROGRESS
·
2019
·Vol. 35
·期 5
·e2846
·
IF 2.406
Yanhong Chang,Shuangming Tong,Hui Luo,Zijia Liu,Bo Qin,Linlin Zhu,Hongxu Sun,Huimin Yu,Zhongyao Shen
In a stirred tank reactor, during catalysis with immobilized cephalosporin C acylase (CCA), the microenvironmental pH dropped to 7.2 in a nonbuffered system (with the pH maintained at 8.5 by adding alkali) due to the existence of diffusional resistance. Moreover, the immobilized CCA only catalyzed five batch reactions, suggesting that the sharp pH gradient impaired the enzyme stability. To buffer the protons produced in the hydrolysis of cephalosporin C by CCA, phosphate and bicarbonate buffers were introduced. When CCA was catalyzed with 0.1 M ammonium bicarbonate buffer, no obvious gradient between the bulk solution and intraparticle pH was detected, and the catalysis of 15 batch reactions was achieved. Accordingly, with 0.2 M ammonium bicarbonate buffer in a packed bed reactor, the immobilized CCA exhibited continuous catalysis with high conversion rates (≥95%) for 21 days. Reactions with ammonium bicarbonate buffer showed significant increases in the stability and catalytic efficiency of the immobilized CCA in different reactors compared to those in nonbuffered systems.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2018
·
IF 4.229
Ya Chu,Lin Gu,Hongmei Du,Konggang Qu,Yan Zhang,Jinsheng Zhao,Yu Xie
In this study, we synthesized a nitrogen rich compound (FPPHA) as the precursor of oxygen reduction reaction (ORR) catalysts, which was prepared based on 1,10-phenanthroline-5-amine and 2,2’-bipyridyl-5,5’-dialdehyde. The FPPHA-Fe complex was formed and be loaded on the carbon powder to form the FPPHA-Fe/C composite catalyst. The pyrolysis of the FPPHA-Fe/C composite was conducted at different temperatures, including 700 °C, 800 °C, and 900 °C, and the resultant pyrolyzed materials were designated to FPPHA-Fe/C-700, FPPHA-Fe/C-800, FPPHA-Fe/C-900, respectively. The physical characteristics of the catalysts were examined by powder X-ray diffraction (PXRD), Brunauer–Emmett–Teller analysis, X-ray photoelectron spectrometer (XPS) and scanning electron microscopy (SEM) etc. The ORR performance of the composite catalysts were evaluated by cyclic voltammetry (CV), linear sweep voltammetry (LSV), and rotating ring disk electrodes (RRDE) in an alkaline solution. The results suggested that the pyrolysis process has a positive effect on the ORR activity of the catalysts, and among the catalysts the Fe-FPPHA/C-800 had the most preferable performance, which reduces oxygen through a predominantly four electron pathway with an average electron transfer number of 3.86 and an average hydrogen peroxide yield of 6.7%.
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NANO
·
2019
·
IF 1.293
Liang Yu,Qingfeng Yi,Xiaokun Yang,Xiulin Zhou
Development of a neutral Zn–air battery is of much significance due to the high stability of zinc in a neutral electrolyte. Here, Ni/Co-doped C–N nanotube composites (C–N, Ni/C–N, Co/C–N, and Ni–Co/C–N) as efficient oxygen reduction reaction (ORR) electrocatalysts in a neutral medium have been prepared by direct pyrolysis of Ni/Co salt, dicyandiamide (DCD) and glucose. Among the synthesized catalysts, Ni–Co/C–N presents a high ORR current density of 8.5 mA ⋅ cm − 2 in a 0.5 mol ⋅ L − 1 KNO 3 solution. The ORR electron transfer number of the catalyst Ni–Co/C–N is 3.8, indicating that O 2 is almost completely reduced to H 2 O. A neutral zinc–air battery utilizing a 0.5 mol ⋅ L − 1 KNO 3 solution has been assembled by using the prepared composite catalyst coated on carbon paper as an air cathode, and Zn plate as an anode. The battery with the cathode catalyst Ni–Co/C–N delivers the open-circuit voltage of 1.13 V and the maximum power density of 65 mW ⋅ cm − 2 . The constant discharge current density of 50 mA ⋅ cm − 2 , 100 mA ⋅ cm − 2 and 150 mA ⋅ cm − 2 can last 202 h, 93 h and 11 h, respectively. A stable voltage plateau appears at various discharge current densities. The neutral zinc–air battery can be repeatedly discharged after replacing the zinc anode. Results indicate that the synthesized Ni–Co/C–N catalyst is an excellent cathode material applied to a neutral zinc–air battery, showing broad application prospects as a mobile power source.
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RSC Advances
·
2019
·Vol. 9
·期 19
·10635-10644
·
IF 3.049
Xiaoxu Xuan,Jun Cheng,Xiao Yang,Junhu Zhou,Kefa Cen
Carbon supported nano-metal catalysts are expected to improve CO2 reduction selectivity and efficiency due to the addition of more active sites and enhancement of electron transport ability. In this study, HKUST-1 was pyrolyzed and decorated with Pt to prepare Pt–Cu/C catalysts. The catalytic effect of the catalysts with different Pt contents in the CO2 photoeletrochemical reduction reaction (CO2PRR) were compared. The total carbon atom conversion rate in CO2PRR experiments using Pt–Cu/C catalysts first increased to a peak when using 1.6 wt% Pt–Cu/C catalyst and then decreased with the increase of Pt content. The 1.6 wt% Pt–Cu/C catalyst showed good hydrogen evolution reaction (HER) inhibiting ability compared with other Pt–Cu/C catalysts. Density functional theory (DFT) calculations were conducted to give an insight into the CO2PRR mechanism on some possible active sites in Pt–Cu/C catalysts. The result demonstrated that HER was more likely to be inhibited on the Cu/Pt active surface and at the same time CO2PRR was promoted.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2018
·
IF 3.141
Jiangdong Dai,Sujun Tian,Yinhua Jiang,Zhongshuai Chang,Atian Xie,Ruilong Zhang,Chunxiang Li,Yongsheng Yan
Here, the magnetic hierarchical porous carbon (MHPC) with micromesopores was first prepared using ethylenediaminetetraacetic acid tripotassium (EDTA-3K) and iron nitrate by simultaneous magnetization/activation method. The optimal product was MHPC-20 with a high graphitization, which possessed a large SBET (1688 m2 g–1) and saturation magnetization (3.679 emu g–1). As expected, MHPC-20 had a very high maximum adsorption capacity (534.2 mg g–1) toward chloramphenicol (CAP) from water solution at 298 K with a positive correlation between SBET and adsorption amount. Additionally, MHPC-20 had a fast adsorption kinetic, only 250 min, and isothermal and kinetics data were well fitted by Langmuir and pseudo-second-order kinetic models, respectively. Moreover, the effect of ion strength, solution pH, and humic acid on CAP adsorption onto MHPC-20 were investigated, indicating a better stability. Besides, MHPC-20 showed good reusability and excellent magnetic separation performance, which implied MHPC-20 as a candidate could be applied in various complex wastewater environments.
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CHINESE JOURNAL OF CATALYSIS
·
2018
·
IF 3.525
Haojie Wang,Chun Chen,Haimin Zhang,Guozhong Wang,Huijun Zhao
Bimetallic nanostructures have attracted great interest as efficient catalyst to enhance activity, selectivity and stability in catalytical conversion. Herein, we report a facile one-pot carbothermal route to in-situ controllable synthesize heterogeneous bimetallic Ni 3 Fe NPs@C nanocatalyst. The X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and N 2 adsorption-description results reveal that the Ni 3 Fe alloy nanoparticles are evenly embedded in carbon matrix. The as-prepared Ni 3 Fe NPs@C catalyst shows excellent selective hydrogenation catalytic performance toward the conversion of levulinic acid (LA) to γ-valerolactone (GVL) via both direct hydrogenation (DH) and transfer hydrogenation (TH). In DH of LA, the bimetallic catalyst achieved a 93.8% LA conversion efficiency with a 95.5% GVL selectivity and 38.2 mmol g −1 h −1 GVL productivity (under 130 °C, 2MPa H 2 within 2 h), which are 6 and 40 times in comparison with monometallic Ni NPs@C and Fe NPs@C catalysts, respectively. In addition, the identical catalyst displayed a full conversion of LA with almost 100% GVL selectivity and 167.1 mmol g −1 h −1 GVL productivity at 180 °C within 0.5 h in TH of LA. Under optimal reaction conditions, the DH and TH catalytic performance of 500-Ni 3 Fe NPs@C(3:1) catalyst for converting LA to GVL is comparable to the state-of-the-art noble-based catalysts. The demonstrated capability of bimetallic catalyst design approach to introduce dual-catalytic functionality for DH and TH reactions could be adoptable for other catalysis processes.
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SENSORS
·
2018
·Vol. 18
·期 6
·1765
·
IF 2.475
Zhen Yang,Huanhuan Wang,Pengfei Guo,Yuanyuan Ding,Chong Lei,Yongsong Luo
Cardiac biomarkers (CBs) are substances that appear in the blood when the heart is damaged or stressed. Measurements of the level of CBs can be used in course of diagnostics or monitoring the state of the health of group risk persons. A multi-region bio-analytical system (MRBAS) based on magnetoimpedance (MI) changes was proposed for ultrasensitive simultaneous detection of CBs myoglobin (Mb) and C-reactive protein (CRP). The microfluidic device was designed and developed using standard microfabrication techniques for their usage in different regions, which were pre-modified with specific antibody for specified detection. Mb and CRP antigens labels attached to commercial Dynabeads with selected concentrations were trapped in different detection regions. The MI response of the triple sensitive element was carefully evaluated in initial state and in the presence of biomarkers. The results showed that the MI-based bio-sensing system had high selectivity and sensitivity for detection of CBs. Compared with the control region, ultrasensitive detections of CRP and Mb were accomplished with the detection limits of 1.0 pg/mL and 0.1 pg/mL, respectively. The linear detection range contained low concentration detection area and high concentration detection area, which were 1 pg/mL–10 ng/mL, 10–100 ng/mL for CRP, and 0.1 pg/mL–1 ng/mL, 1 n/mL–80 ng/mL for Mb. The measurement technique presented here provides a new methodology for multi-target biomolecules rapid testing.Keywords:myoglobin;C-reactive protein;Dynabeads;magnetoimpedance;microfluidic device
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FEMS MICROBIOLOGY LETTERS
·
2018
·Vol. 365
·期 5
·
IF 1.735
Ke Xia,Xia Xiao-Yuan,Zheng Ren-Chao,Zheng Yu-Guo
The Erg28p protein is localized to the endoplasmic reticulum, where it acts as a scaffold to tether the C-4 demethylase complex involved in the sterol biosynthesis pathway of Saccharomyces cerevisiae. However, due to the challenges involved in characterizing the interactions of membrane proteins, the precise region of Erg28p that is responsible for the assembly of this enzyme complex remains unknown. To address this question, mutants with serial truncations in the C-terminus of Erg28p were constructed based on a topology prediction of its transmembrane domain. Sterol profiles demonstrated that intermediates involved in the stepwise removal of the two C-4 methyl groups from the tetracyclic sterol ring were accumulated in the ERG28Δ135-447 strain. Homologous alignment of Erg28p further identified a highly conserved 10-amino acid sequence (63LS/QARTFGT/LWT72) within the truncated region of ERG28Δ136-273. Complementation of the BY4741/erg28 strain with the ScERG28Δ175-204 plasmid resulted both in a significant growth inhibition and a reduction of ergosterol biosynthesis compared with the plasmid without the Δ175-204 truncation. Furthermore, homology modeling of the Erg28p mutant indicated that the deletion of residues 63–72 significantly disrupted the 3D structure of the four parallel helices in Erg28p. Taken together, the data indicate that the region spanning amino acids 63–72 constitutes a key consensus motif within Erg28p that is required for sterol C-4 demethylation during ergosterol biosynthesis in S. cerevisiae.
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CHEMICAL ENGINEERING JOURNAL
·
2018
·
IF 6.735
Ying Liu,Xiaoyan Chen,Yulin Yang,Yong Feng,Deli Wu,Shun Mao
Cobalt-based nanostructures have shown a great potential for radical production by activating persulfate (PS). Here, we report a facile strategy to synthesize nitrogen-doped porous Co@C nanoboxes (Co@NC) by pyrolysis of zeolitic imidazolate frameworks (ZIF-67), followed by partially etching away the metallic cobalt. With a nitrogen-enriched hollow porous carbon nanobox and embedded Co nanoparticles, the Co@NC shows high efficiency in PS activation for p-Chloroaniline (PCA) removal. The degradation study shows that a complete removal of high concentration PCA is done within two minutes, which is superior to most of the reported PCA removals with PS-based advanced oxidation processes (AOPs). More importantly, the Co@NC exhibits high catalytic activities in a wide range of pH from 5 to 9. The Co@NC also shows very limited Co 2+ release with a dissolution proportion of 0.28%, much lower than previously reported Co-based catalysts, and remains high efficiency after five successive reaction cycles. A heterogeneous activation mechanism though surface reaction is proposed, in which PCA firstly absorbs on the carbon nanobox surface, then being oxidized by generated radicals and non-radical species. The unique structure and outstanding performance of Co@NC catalysts present new insights in catalyst design for PS-based advanced oxidation for organic pollutants removal in waste water.
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TALANTA
·
2018
·
IF 4.244
Shiyu Zhang,Can Chen,Xiaofei Qin,Qianchen Zhang,Jinhua Liu,Jixin Zhu,Yongqian Gao,Lin Li,Wei Huang
Trypsin, as one of important proteases, is specific for catalyzing the hydrolysis of peptide and ester bonds containing lysine and arginine residues at the C-terminus. The level of trypsin in biological fluids can serve as a reliable and specific diagnostic biomarker for pancreatic function and its pathological changes. Herein, we demonstrate the application of phosphorescent Cu NCs for trypsin detection for the first time depending on the electron transfer between Cu NCs and cyt c. Cyt c and Cu NCs were selected as the quencher and the fluorophore, respectively. Cu NCs could bind to the positively charged cyt c through electrostatic and hydrophobic interactions, and the phosphorescence of Cu NCs was efficiently quenched by the metal-containing heme of cyt c. In the presence of trypsin, cyt c was digested, thus phosphorescence of Cu NCs remained. Therefore, a new and continuous phosphorescence assay for the detection of trypsin activity and its inhibitor screening was established. The plot of relative fluorescence versus trypsin concentration obtains a good linear detection range from 0 to 20 ng/mL (R 2 = 0.9657), and a detection limit of 2 ng/mL, which is much lower than 20 ng/mL of the sensor in buffer solution because of urine amplifying the phosphorescence signal of Cu NCs based on the FRET strategy. This assay still has been successfully applied to trypsin inhibitor screening, demonstrating its potential application in drug discovery.
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JOURNAL OF MATERIALS SCIENCE
·
2017
·Vol. 53
·期 5
·3443-3454
·
IF 2.599
Liu Jiao,Jiang Peng-peng,He Chun,Jiang Xiao-hong,Lu Lu-de
Here, novel and stable core–shell silver–carbon nanocomposites (Ag@CSs) were obtained using glucose as the carbon source and stabilizer, silver nitrate as the silver source, and trioctylamine (TOA) as the soft template and extractant. It is worth mentioning that the shape of the silver core shows the hexagon shape, and we consider that TOA and glucose selectively adsorb the Ag (111) crystal face resulting in this growth pattern of the silver core. Owing to the enhanced local field effect around their sharp corners and edges, such structure exhibits superior properties for the surface-enhanced Raman scattering (SERS) enhancement. The hydrothermal carbon shell not only effectively avoids the agglomeration of Ag nanoparticles core, but also serves as a protective layer of the SERS active nanostructure during the whole course of the experiment. In addition, the thickness of the loose shell was significantly reduced after the product was stored in ethanol solution for a period of time. It is found that dropped cast probe molecules onto Ag@CSs have a lower SERS activity, while that immersed in the probe molecular solution for a period of time have a higher SERS activity, indicating that the detection of the probe molecules using this Ag@CSs substrate may require an interactive process. The results show that the as-obtained Ag@CSs hold tremendous potential for SERS applications for its long-term stability and superior SERS performance.
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