ACS Applied Nano Materials
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2019
·
IF 0
Sefiu Abolaji Rasaki,Hangjia Shen,Tiju Thomas,Minghui Yang
Transition metal carbides have received significant attention for oxygen reduction reaction (ORR) applications primarily owing to their good conductivity. However, cobalt carbide based catalysts (CoCx) are difficult to prepare, owing to the preferential formation of metallic cobalt and cobalt oxide instead. Also, cobalt carbide nanoparticles rapidly coarsen and undergo grain growth. This is a problem as it results in low current density and poor active site exposures. In this study, carbon-supported CoCx (C@CoCx) is successfully synthesized using the solid–solid separation synthesis method. The limitations identified to be associated with cobalt carbide nanoparticle based electrocatalysts are overcome. Here, the synthetic approach ensures good distribution and protection of CoCx on in situ generated carbon nanotubes. This results in robust activities with an appreciable onset potential of ∼0.92 V, a half-wave potential of ∼0.8 V, and a durability of ∼100% (tested on ∼22 h continuous operation runs). In alkaline medium, C@CoCx compares favorably with commercial platinum dispersed on carbon (20 wt % Pt/C) and shows a higher current density of ∼300 μA/cm2 at an electrode potential of 0.6 V. All of these indicate that there is a synergistic charge transfer between CoCx and an in situ generated carbon nanotube. This is due to intimate contact that exists between the two phases; it is in fact responsible for superior methanol tolerance observed, making it a good candidate for direct methanol fuel cells.
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JOURNAL OF MATERIALS SCIENCE
·
2019
·Vol. 54
·期 11
·8216-8225
·
IF 3.442
Xu Wen,Cao Bo,Lin Hechun,Cheng Wenjuan,Luo Chunhua,Peng Hui,Duan Chungang
The catalytic activities of three topotactic phase strontium cobaltites (SCO, hexagonal, orthorhombic and tetragonal) for H 2 O 2 decomposition were studied. All they present excellent catalytic activity with good stability at cycled test, and the mesoporous tetragonal SCO exhibits the best activity. Detailed kinetic research indicates the zero-order process of H 2 O 2 decomposition. Increasing the temperature will accelerate the reactions greatly with the controlled temperature in the range of 20–45 °C. The calculated active energy ( E a ) for H-SCO, O-SCO and T-SCO is 93.2, 85.1 and 87.5 (kJ/mol), respectively. The efficient catalytic degradation of Rhodamine B illustrates that SCO is a kind of promising catalysis for the advanced oxidation process.
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TALANTA
·
2019
·
IF 4.916
Shuyan Ge,Jingbo He,Chenxing Ma,Jiyang Liu,Fengna Xi,Xiaoping Dong
Heteroatom doping can endow graphene quantum dots (GQDs) with various new or improved structural, optical and physicochemical properties. In contrast to the widely reported oxygen, nitrogen or sulfur doping in GQDs, simple and scalable synthesis of boron-doped GQDs (B-GQDs) with high yield and quantum yields remains challenge. In this work, B-GQDs are one-step synthesized and serve as the fluorescence probes for the fabrication of sensors towards Fe 3+ ion or phosphate (Pi) as well as biosensor towards cytochrome C (Cyt C). The B-GQDs are facile synthesized using one-step bottom-up molecular fusion between 1,3,6-trinitropyrene and borax in sodium hydroxide under hydrothermal process. The synthesis can be performed using large volume autoclave (500 ml) with a high yield of 71%, indicating possibility for gram-scale production of B-GQDs. The as-prepared B-GQDs exhibit single or bilayer graphene structure, high crystallinity , uniform size, bright (absolute photoluminescence quantum yield of 16.8%) and excitation-independent green fluorescence (maximum excitation wavelength and emission wavelength of 480 nm and 520 nm, respectively). Successful doping of B atoms in the lattice of GQDs enables high selectivity towards Fe 3+ . Based on quenching of fluorescence of B-GQDs by Fe 3+ (turn-off model), detection of Fe 3+ (with limit of detection-LOD of 31.2 nM) and Fe 3+ -rich Cyt C (with LOD of 5.9 μg/ml) are demonstrated. As Pi can recover Fe 3+ -quenched fluorescence of B-GQDs (turn-off-on model), indirect fluorescent detection of Pi is also achieved with LOD of 340 nM. In addition, detection of Fe 3+ , Cyt C and Pi in real samples is achieved.
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PubMed
高影响因子
SOLID STATE SCIENCES
·
2019
·
IF 2.155
Jianxun Zhao,Xiangjun Zhou,Yalan Guo,Zhongmin Su,Heng Liu,Wanqiang Liu,Shang Gao
Co 0.9 Cu 0.1 Si alloy was fabricated via mechanical alloying technique. Different amount of palladium was doped into the Co 0.9 Cu 0.1 Si alloy by ball milling. The composite alloy combined the excellent electrocatalysis activity of Pd, exhibiting preferable electrochemical performance than the original alloy. The Co 0.9 Cu 0.1 Si + 5 wt% Pd composite showed a C max of 559.2 mAh/g, significantly higher than that for Co 0.9 Cu 0.1 Si (502.1 mAh/g). The cycle stability was also enhanced after Pd loading. Moreover, the effect of ball milling time on electrochemical performance for the composite alloy was also investigated. 5 wt% Pd was mixed with the Co 0.9 Cu 0.1 Si alloy at different ball milling time (0.5 h, 1 h, 2 h, 3 h and 5 h). The optimal discharge capacity, capacity retention and high-rate dischargeability were obtained under the ball milling time of 2 h. The studies on electrochemical reaction kinetics demonstrated that the addition of Pd could accelerate the charge-transfer, thus enhancing the electrochemical activity and reaction kinetics of the alloy. The results indicated that Pd loading was an effective way in enhancing the electrochemical performance of Co 0.9 Cu 0.1 Si alloy.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
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2019
·
IF 8.355
Yuhao Cai,Bing Tang,Liying Bin,Shaosong Huang,Ping Li,Fenglian Fu
This work prepared a novel adsorbent with multi-layer structure and verified its adsorption mechanism for various ionic dyes. By the methods of cross-linking and surface modification, a multi-layer composite (CTAB-Chitosan@Al 2 O 3 ) was successfully synthesized, which showed an excellent adsorptive performance for various anionic dyes. The results indicated that the outer layer and the core adsorbed Congo Red (CO) and Reactive Blue (RB) well, and the middle layer played a leading role on adsorbing Methyl Orange (MO). The maximum adsorption capacity of CTAB-Chitosan@Al 2 O 3 for MO, CO and RB was 327.87, 1250.00 and 1017.90 mg/g, respectively. The characteristics of the as-synthesized adsorbent were revealed by multi-method, including Fourier Transform Infra-Red spectra, X-ray powder diffraction, X-ray photoelectron spectra, Scanning Electron Microscope, Brunauer-Emmet-Teller surface area and Thermogravimetric analyzer, which verified that the comprehensive effects of electrostatic interaction and hydrogen bond was the main mechanism for CTAB-Chitosan@Al 2 O 3 to adsorb ionic dyes. The pH value obviously influenced the surface charge of CTAB-Chitosan@Al 2 O 3 , and it was a convenient approach to regulate and control the adsorption process by only adjusting the pH value.
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CHEMICAL PAPERS
·
2019
·Vol. 74
·期 2
·485-497
·
IF 1.246
Quan Cong,Liu Jiayu,Sun Wei,Cheng Xinjian
It is extremely necessary to detect heavy metals sensitively and selectively, especially the ions that will cause great harm to humans and the environment. This work deals with two fluorescent chemosensors and their outstanding role when detecting Zn 2+ and Cd 2+ ions. First, a small molecular chemosensor (TPB) has been designed and synthesized via Suzuki reaction using one part of benzene-1,3,5-triyltriboronic acid and three parts of 2-bromo-1, 10-phenanthroline as starting materials. And then, its corresponding macromolecular fluorescent chemosensor (PTPB) was synthesized. The infrared spectra, mass spectrometry (MS), and 1 H-NMR were used to study the structures of TPB and PTPB. From what has been studied, the TPB and PTPB were stable in a relative wide pH range. As soon as the Cd 2+ and Zn 2+ ions added, fluorescence of the two sensors TPB and PTPB was changed obviously. In addition, PTPB was found have better performance to both Cd 2+ and Zn 2+ than TPB through the ‘‘molecular wire’’ mechanism. Job’s plots were also be tested, showing that the combination ratio of TPB and PTPB to Cd 2+ and Zn 2+ were both 3:1 (ion/sensor). In addition, the minimum detection limits of the macromolecular chemosensor PTPB for Cd 2+ and Zn 2+ reached 0.424 μM and 1.27 μM, respectively.
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高影响因子
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
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2019
·
IF 2.931
Shengmei Song,Fan Liang,Minglu Li,Fangfang Du,Wenjuan Dong,Xiaojuan Gong,Shaomin Shuang,Chuan Dong
A fluorescent sulfur and nitrogen dual-doped carbon dots (S,N-CDs) was prepared by a simple and one-step acid-base neutralization and exothermic carbonization method. Hexavalent chromium (Cr(VI)) could effectively quench the fluorescence of S,N-CDs based on inner filter effect (IFE) and dynamic quenching, whereas ascorbic acid (AA) could recover the fluorescence of S,N-CDs/Cr(VI) because of IFE weakening. So an “on-off-on” and label-free nano-probe consecutive determination of Cr(VI) and AA was constructed. This nano-probe system demonstrated excellent selectivity and sensitivity to Cr(VI) and AA with linear range of 0.065–198 μmol/L (3.38–10,296 μg/L) and 6.6–892 μmol/L (1.16–157 mg/L), respectively. Meanwhile, the as-prepared S,N-CDs possess low toxicity and could be used for multi-color cell imaging in SMMC 7721 cells. More importantly, this nano-probe was successfully employed for detection of Cr(VI) in tap water and AA in food samples. In view of its simple detection condition, rapid response, wide linear range, low detection limit and inexpensive instrument, the as-constructed nano-probe system could have a wide range of potential application, including water quality monitoring and evaluation, food inspection and testing and biomedical analysis.
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PubMed
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2019
·
IF 4.084
Darvaish Khan,Jianxin Zou,Mingguang Pan,Zhewen Ma,Wen Zhu,Tianping Huang,Xiaoqin Zeng,Wenjiang Ding
In this study, MgH 2 and Co powders were mechanically milled in the molar ratio 2:1 and compressed to hard-packed cylindrical pellets. The microstructure, phase changes, and hydrogen storage properties of the mechanically milled 2MgH 2 Co powder and the 2MgH 2 Co compressed pellet were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and synchronous thermal (DSC/TG) analyses. Dehydrogenation of the 2MgH 2 Co compressed pellet is mainly due to the decomposition of Mg 2 CoH 5 while it is the dehydriding of MgH 2 for the milled 2MgH 2 Co powder. Pressure composition absorption isotherms of the 2MgH 2 Co powder and 2MgH 2 Co compressed pellet show two and three plateaus, respectively, corresponding to the formation of Mg 6 Co 2 H 11 and Mg 2 CoH 5 hydride phases . For the compressed 2MgH 2 Co pellet, enthalpies of formation/decomposition were measured to be −58.11±7.69 kJ/mol H 2 /55.70±3.34 kJ/mol H 2 for Mg 2 CoH 5 and -81.89±10.39 kJ/mol H 2 /74.47±5.27 kJ/mol H 2 for Mg 6 Co 2 H 11 . In contrast, hydrogenation/dehydrogenation enthalpies of Mg 2 CoH 5 and Mg 6 Co 2 H 11 mechanically milled 2MgH 2 Co powder were −73.98±10.1 kJ/mol H 2 /71.67±1.38 kJ/mol H 2 and -96.86±8.73 kJ/mol H 2 /89.95±10.81 kJ/mol H 2 , respectively. Fast hydrogenation was observed in the dehydrided 2MgH 2 Co compressed pellet with about 2.75 wt% absorbed in less than 1 min at 300 °C and a maximum hydrogen storage capacity of 4.43 wt% (2.32 wt% for the 2MgH 2 Co powder) was achieved. The hydrogen absorption activation energy of the 2MgH 2 Co compressed pellet (64.34 kJ-mol −1 H 2 ) is lower than the mechanically milled 2MgH 2 Co powder (73.74 kJ-mol −1 H 2 ). The results show that mechanical milling followed by high-pressure compression is an efficient method for the synthesis of Mg-based complex hydrides with superior hydrogen sorption properties .
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高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2019
·
IF 3.131
Haibin Li,Li Ma,Liya Zhou,Jing Gao,Zhihong Huang,Ying He,Yanjun Jiang
The combination of metal nanoparticle-catalysts and biocatalysts to perform cascade catalytic strategy is a powerful platform for synthesis or degradation of complex molecules. In this work, an integrated nanoreactor (INR) was successfully prepared via immobilizing organophosphorus hydrolase (OPH) onto porous carbon materials containing Co nanoparticles (C/Co). The C/Co was synthesized conveniently by pyrolysis of a metal-organic framework (MOF) named ZIF-67. This INR can reduce the toxicity of organophosphate nerve agent up to 208-fold by cascade degradation route. In this INR, C/Co not only acts as chemocatalyst but also serves as support for OPH, which allows an easy separation and reuse due to its magnetic properties. Moreover, this INR shows outstanding universal applicability, reusability and stability. With this proof-of-concept, it is foreseeable that the future metal nanoparticles that formed by pyrolyzing MOF will combine more other biocatalysts for perspective applications in more fields.
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Nature Energy
·
2018
·Vol. 3
·期 12
·1067-1075
·
IF 46.859
Gao Wenbo,Guo Jianping,Wang Peikun,Wang Qianru,Chang Fei,Pei Qijun,Zhang Weijin,Liu Lin,Chen Ping
Ammonia is a promising carbon-free energy carrier, but is currently synthesized industrially under harsh conditions. Synthesizing ammonia using lower temperatures and pressures could therefore improve its prospects as a chemical means to store and transport energy. Here we report that alkali and alkaline earth metal imides function as nitrogen carriers that mediate ammonia production via a two-step chemical looping process operating under mild conditions. Nitrogen is first fixed through the reduction of N 2 by alkali or alkaline earth metal hydrides to form imides and, subsequently, the imides are hydrogenated to produce NH 3 and regenerate the metal hydrides. The oxidation state of hydrogen therefore switches between −1 (hydride), 0 (H 2 ) and +1 (imide and NH 3 ). Late 3d metals accelerate the reaction rates of both steps. The chemical loop mediated by BaNH and catalysed by Ni produces NH 3 at 100 °C and atmospheric pressure.
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高影响因子
ELECTROANALYSIS
·
2018
·Vol. 30
·期 11
·2768-2773
·
IF 2.851
Xin Feng,Xiaomei Dong,Qingcheng Zhang,Cuixia Cui,JingJing Zhang,Zhen Chen,Changmi Wu,Huile Jin,Shun Wang,Jichang Wang
In this study carbon materials with a hierarchical pore structure have been fabricated through a scalable and template free solvothermal method in the presence of metal catalysts, where the presence of metal catalysts was found to be essential for the initial polymerization process. The as-prepared carbon contained trace amounts of metal residues and exhibited highly efficient catalytic activity toward the oxygen reduction reaction (ORR). Among all the metal catalysts studied, cobalt containing porous carbon exhibited the highest ORR electrocatalytic activity with great tolerance to methanol crossover and excellent long-term cycling stability, outperforming the commercial 30 % ( w / w ) Pt/C catalysts. The great performance may be contributed to the unique porous structure, the large specific surface area of cobalt-doped carbon and chemical activity of cobalt. The result provides useful guidance for the development of carbon-based electrocatalysts.
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高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2018
·
IF 4.229
Jianxun Zhao,Xiaojie Zhai,Xing Tao,Heng Liu,Wanqiang Liu,Dayong Jiang,Shang Gao
Mechanical alloying technique was used to prepare the Co 0.9 Cu 0.1 Si alloy. Composite materials of Co 0.9 Cu 0.1 Si doping with different amounts of multi-walled carbon nanotubes (MWCNTs) or lithium modified MWCNTs (Li-MWCNTs) were obtained via ball-milling to improve the hydrogen storage performance of Co 0.9 Cu 0.1 Si. XRD , SEM and TEM were used to analysis the structural properties of the samples. A three-electrode battery system was carried out to test the electrochemical properties . After the addition of MWCNTs, the composites showed higher discharge capacity, stronger HRD, better cyclic stability and lower charge-transfer resistance than the original Co 0.9 Cu 0.1 Si alloy. The electro-catalytic function of MWCNTs, the reduction of particle size and the raise of specific surface area for Co 0.9 Cu 0.1 Si alloy may provide larger electrochemically accessible area and rapid channel for hydrogen transportation , which are important to enhance the electrochemical performance of the alloy. Moreover, a further improvement was achieved after the addition of Li-MWCNTs, illustrating that the MWCNTs and lithium species had synergistic effects in improving the discharge capacity and reaction kinetics of the Co 0.9 Cu 0.1 Si alloy electrode. As the weight ratio of the alloy and Li-MWCNTs was 15:1, the optimal discharge capacity of 624.4 mAh/g and the highest capacity retention of 67.5% were achieved.
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高影响因子
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