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1.
ACS Appl Mater Interfaces ; 11(27): 24184-24191, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31184464

RESUMO

The development of highly efficient and stable cathodes for sodium-ion batteries (SIBs) is strategically critical to achieving large-scale electrical energy storage. Creating air-stable and high-voltage layered cathodes for sodium-ion full batteries still remains a challenge. Herein, we describe a rational design and preparation of a stable P3-Na2/3Ni1/4Mg1/12Mn2/3O2 cathode. The cathode displays a satisfactory working voltage of 3.6 V and excellent cyclic stability over 100 cycles at a 1 C rate without obvious capacity fading. The results of ex situ X-ray diffraction (XRD) demonstrate that the P3-type structure is well retained even when charged to 4.4 V. Furthermore, the structural characterization by XRD Rietveld refinement, scanning electron microscopy, and electrochemical testing certifies that the cathode maintains its structure commendably even when soaked in water for 12 h. In particular, the P3- Na2/3Ni1/4Mg1/12Mn2/3O2∥hard carbon full battery exhibits a desired competitively high voltage of 3.45 V and an attractive energy density of up to 412.2 W h kg-1 based on the cathode. The comprehensive results achieved by the specially designed strategy provide guidance toward the exploration of stable cathodes in the application of SIBs as modern energy-storage devices.

2.
Chem Commun (Camb) ; 55(43): 6134, 2019 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-31073586

RESUMO

Correction for 'NiS2 nanodotted carnation-like CoS2 for enhanced electrocatalytic water splitting' by Weili Xin et al., Chem. Commun., 2019, 55, 3781-3784.

3.
Chem Commun (Camb) ; 55(26): 3781-3784, 2019 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-30864580

RESUMO

Combining ultrasmall NiS2 nanodots with three-dimensional carnation-like CoS2 microstructures is demonstrated to be able to enhance the electrocatalytic activities for both the oxygen and hydrogen evolution reactions, leading to efficient overall alkaline water splitting.

4.
Chem Commun (Camb) ; 54(64): 8909-8912, 2018 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-30042999

RESUMO

Bimetallic sulfide ((Ni0.3Co0.7)9S8) nanoparticles confined by dual-carbon nanostructures are prepared by pyrolyzing a mixture of surfactant-intercalated layered double hydroxide and melamine, and deliver a highly reversible capacity and decent rate capability as anode nanomaterials for lithium- and sodium-ion batteries.

5.
Front Plant Sci ; 9: 407, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29643864

RESUMO

We present a high throughput crop physiology condition monitoring system and corresponding monitoring method. The monitoring system can perform large-area chlorophyll fluorescence imaging and multispectral imaging. The monitoring method can determine the crop current condition continuously and non-destructively. We choose chlorophyll fluorescence parameters and relative reflectance of multispectral as the indicators of crop physiological status. Using tomato as experiment subject, the typical crop physiological stress, such as drought, nutrition deficiency and plant disease can be distinguished by the monitoring method. Furthermore, we have studied the correlation between the physiological indicators and the degree of stress. Besides realizing the continuous monitoring of crop physiology, the monitoring system and method provide the possibility of machine automatic diagnosis of the plant physiology. Highlights: A newly designed high throughput crop physiology monitoring system and the corresponding monitoring method are described in this study. Different types of stress can induce distinct fluorescence and spectral characteristics, which can be used to evaluate the physiological status of plants.

6.
Small ; 14(19): e1800367, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29633498

RESUMO

Exploring highly efficient and stable oxygen evolution reaction (OER) electrocatalysts such as transition-metal phosphides (TMPs) is critical to advancing renewable hydrogen fuel. TMP nanostructures typically involving binary or ternary TMPs tuned by cation or anion doping are suggested to be promising low-cost and durable OER catalysts. Herein, the preparation of CoP/CoP2 composite nanoparticles encapsulated within N,P-doped carbon nanotubes (CoP/CoP2 @NPCNTs) is demonstrated as a synergistic electrocatalyst for OER via the calcination of a CoAl-layered double hydroxide/melamine mixture and subsequent phosphorization. Facile visualization by scanning electron microscopy in conjunction with electron backscatter diffraction demonstrates the encapsulation of the CoP/CoP2 nanoparticles within the N,P-codoped CNTs. Electrocatalytic evaluation shows that the composite electrode requires a low overpotential of 300 mV for the OER at 10 mA cm-2 in a 1.0 m KOH solution and, in particular, exhibits an excellent long-term durability of ≈100 h, which is superior to that of the state-of-the-art RuO2 electrocatalyst. Density functional theory calculations reveal that the synergistic effect of CoP and CoP2 can enhance the electrocatalytic performance. In addition, molecular dynamics simulations demonstrate that the generated O2 molecules can readily diffuse out of the CNTs. Both the effects give rise to the observed OER enhancement.

7.
Appl Opt ; 56(35): 9762-9769, 2017 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-29240123

RESUMO

For both field and greenhouse crops, it is challenging to evaluate their growth information on a large area over a long time. In this work, we developed a chlorophyll fluorescence imaging-based system for crop population growth information detection. Modular design was used to make the system provide high-intensity uniform illumination. This system can perform modulated chlorophyll fluorescence induction kinetics measurement and chlorophyll fluorescence parameter imaging over a large area of up to 45 cm×34 cm. The system can provide different lighting intensity by modulating the duty cycle of its control signal. Results of continuous monitoring of cucumbers in nitrogen deficiency show the system can reduce the judge error of crop physiological status and improve monitoring efficiency. Meanwhile, the system is promising in high throughput application scenarios.


Assuntos
Clorofila , Produtos Agrícolas/crescimento & desenvolvimento , Cucumis sativus/crescimento & desenvolvimento , Fluorescência , Iluminação , Fotossíntese/fisiologia , Produtos Agrícolas/química , Cucumis sativus/química , Temperatura Alta , Iluminação/instrumentação , Iluminação/métodos , Fotografação/métodos
8.
ACS Appl Mater Interfaces ; 9(49): 42742-42750, 2017 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-29182850

RESUMO

Transition-metal sulfides (TMSs) are suggested as promising electrode materials for electrochemical pseudocapacitors and lithium- and sodium-ion batteries; however, they typically involve mixed composites or conventionally stoichiometric TMSs (such as NiCo2S4 and Ni2CoS4). Herein we demonstrate a preparation of solid-solution sulfide (Ni0.7Co0.3)S2 supported on three-dimensional graphene aerogel (3DGA) via a sulfuration of NiCo-layered double hydroxide (NiCo-LDH) precursor/3DGA. The electrochemical tests show that the (Ni0.7Co0.3)S2/3DGA electrode exhibits a capacitance of 2165 F g-1 at 1 A g-1, 2055 F g-1 at 2 A g-1, and 1478 F g-1 at 10 A g-1; preserves 78.5% capacitance retention upon 1000 cycles for pseudocapacitors; and in particular, possesses a relatively high charge capacity of 388.7 mA h g-1 after 50 cycles at 100 mA g-1 as anode nanomaterials for sodium-ion batteries. Furthermore, the electrochemical performances are readily tuned by varying the cationic type of the tunable LDH precursors to prepare different solid-solution sulfides, such as (Ni0.7Fe0.3)S2/3DGA and (Co0.7Fe0.3)S2/3DGA. Our results show that engineering LDH precursors can offer an alternative for preparing diverse transition-metal sulfides for energy storage.

9.
Nanoscale ; 9(17): 5677-5685, 2017 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-28426060

RESUMO

Transition metal phosphide (TMP) nanostructures have stimulated increasing interest for use in water splitting owing to their abundant natural sources and high activity for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Typically, the preparation of hierarchical TMPs involves the utilization of expensive or dangerous phosphorus sources, and, in particular, the understanding of topotactic transformations of the precursors to crystalline phases-which could be utilized to enhance electrocatalytic performance-remains very limited. We, herein, report a controllable preparation of CoP/CoP2 nanoparticles well dispersed in flower-like Al2O3 scaffolds (f-CoP/CoP2/Al2O3) as a bifunctional electrocatalyst for the HER and OER via the phosphorization of a flower-like CoAl layered double hydroxide precursor. Characterization by in situ X-ray diffraction (XRD) monitored the topotactic transformation underlying the controllable formation of CoP/CoP2via tuning the phosphorization time. Electrocatalytic tests showed that an f-CoP/CoP2/Al2O3 electrode exhibited a lower onset potential and higher electrocatalytic activity for the HER and OER in the same alkaline electrolyte than electrodes of flower-like and powdered CoP/Al2O3. The enhanced electrochemical performance was experimentally supported by measuring the electrochemically active surface area. The f-CoP/CoP2/Al2O3 composite further generated a current density of 10 mA cm-2 at 1.65 V when used as a bifunctional catalyst for overall water splitting. Our results demonstrate that the preparation route based on the LDH precursor may provide an alternative for investigating diverse TMPs as bifunctional electrocatalysts for water splitting.

10.
Sci Rep ; 7: 42172, 2017 02 08.
Artigo em Inglês | MEDLINE | ID: mdl-28176843

RESUMO

Developing effective heterogeneous metal catalysts with high selectivity and satisfactory activity for chemoselective hydrogenation of alkyne to alkene is of great importance in the chemical industry. Herein, we report our efforts to fabricate TiO2-supported Pd catalysts by a photodeposition method at room temperature for phenylacetylene semihydrogenation to styrene. The resulting Pd/TiO2 catalyst, possessing smaller Pd ensembles with ambiguous lattice fringes and more low coordination Pd sites, exhibits higher styrene selectivity compared to two contrastive Pd/TiO2 samples with larger ensembles and well-organized crystal structure fabricated by deposition-precipitation or photodeposition with subsequent thermal treatment at 300 °C. The sample derived from photodeposition exhibits greatly slow styrene hydrogenation in kinetic evaluation because the disordered structure of Pd particles in photodeposited Pd/TiO2 may prevent the formation of ß-hydride phases and probably produce more surface H atoms, which may favor high styrene selectivity.

11.
ACS Appl Mater Interfaces ; 8(48): 32853-32861, 2016 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-27934161

RESUMO

Layered double hydroxides (LDHs), also known as hydrotalcite-like anionic clay compounds, have attracted increasing interest in electrochemical energy storage, in the main form of LDH precursor-derived transition metal oxides (TMOs). One typical approach to improve cycling stability of the LDH-derived TMOs is to introduce one- and two-dimensional conductive carbonaceous supports, such as carbon nanotubes and graphene. We herein demonstrate an effective approach to improve the electrochemical performances of well-dispersed biactive NiCo2S4/Ni0.96S as anode nanomaterials for lithium-ion batteries (LIBs), by introducing a three-dimensional graphene aerogel (3DGA) support. The resultant 3DGA supported NiCo2S4/Ni0.96S (3DGA/NCS) composite, obtained by sulfuration of NiCo-layered double hydroxide (NiCo-LDH) precursor in situ grown on the 3DGA support (3DGA/NiCo-LDH). Electrochemical tests show that the 3DGA/NCS composite indeed delivers the greatly enhanced electrochemical performances compared with the NiCo2S4/Ni0.96S counterpart on two-dimensional graphene aerogel, i.e., a high reversible capacity of 965 mA h g-1 after 200 cycles at 100 mA g-1 and especially a superlong cycling stability of 620 mA h g-1 after 800 cycles at 1 A g-1. The enhancements could be ascribed to the compositional and structural advantages of boosting electrochemical performances: (i) well-dispersed NiCo2S4/Ni0.96S nanoparticles with interfacial nanodomains resulting from both the dual surface confinements of the 3DGA support and the crystallographic confinement of NiCo-well-arranged LDH crystalline layer, (ii) an appropriate specific surface area and a wide pore size distribution of mesopores and macropores, and (iii) highly conductive 3DGA support that is measured experimentally by using electrochemical impedance spectra to underlie the enhancement. Our results demonstrate that the tunable LDH precursor-derived synthesis route may be extended to prepare various transition metal sulfides and even transition metal phosphides for energy storage with the aid of tunable cationic type and molar ratio.

12.
Sci Rep ; 6: 22748, 2016 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-26951794

RESUMO

High efficient and sustainable utilization of water-based lubricant is essential for saving energy. In this paper, a kind of layered double hydroxide (LDH) nanoplatelets is synthesized and well dispersed in water due to the surface modification with oleylamine. The excellent tribological properties of the oleylamine-modified Ni-Al LDH (NiAl-LDH/OAm) nanoplatelets as water-based lubricant additives are evaluated by the tribological tests in an aqueous environment. The modified LDH nanoplatelets are found to not only reduce the friction but also enhance the wear resistance, compared with the water-based cutting fluid and lubricants containing other particle additives. By adding 0.5 wt% LDH nanoplatelets, under 1.5 GPa initial contact pressure, the friction coefficient, scar diameter, depth and width of the wear track dramatically decrease by 83.1%, 43.2%, 88.5% and 59.5%, respectively. It is considered that the sufficiently small size and the excellent dispersion of NiAl-LDH/OAm nanoplatelets in water are the key factors, so as to make them enter the contact area, form a lubricating film and prevent direct collision of asperity peaks. Our investigations demonstrate that the LDH nanoplatelet as a water-based lubricant additive has a great potential value in industrial application.

13.
J Colloid Interface Sci ; 462: 183-90, 2016 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-26454377

RESUMO

Low-content ultrathin coating of non-active alumina (Al2O3) has been extensively utilized as one of the most effective strategies to improve electrochemical performances of electrodes for lithium-ion batteries (LIBs), however, typically by employing expensive atomic layer deposition equipment. We herein demonstrate a simple preparation of high-content and well-dispersed Al2O3 (24.33wt.%)-containing multi-component composite (CoO/Co3O4/N-C/Al2O3) by calcination of melamine/CoAl-layered double hydroxide (CoAl-LDH) mixture. The resulting composite bundles the advantages expected to improve electrochemical performances: (i) bi-active CoO/Co3O4, (ii) highly conductive N-doped carbon, and (iii) N-doped carbon and high-content non-active Al2O3 as buffering reagents, as well as (iv) good distribution of bi- and non-active components resulted from the lattice orientation and confinement effect of the LDH layers. Electrochemical evaluation shows that the composite electrode delivers a highly enhanced reversible capacity of 1078mAhg(-1) after 50cycles at 100mAg(-1), compared with the bi-active CoO/Co3O4 mixtures with and without non-active Al2O3. Transmission electron microscopy/scanning electron microscopy observations and electrochemical impedance spectra experimentally provide the information on the good distributions of multiple components and the improved conductivity underlying the enhancements, respectively. Our LDH precursor-based preparation route may be extended to design and prepare various multi-component transition metal oxides for efficient lithium storage.

14.
Langmuir ; 31(24): 6704-12, 2015 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-26033419

RESUMO

Thin films of nickel-aluminum-containing layered double hydroxide (NiAl-LDH) have been prepared on nickel foil and nickel foam substrates by secondary (seeded) growth of NiAl-LDH seed layer. The preparation procedure consists of deposition of LDH seeds from a colloidal suspension on the substrate by dip coating, followed by hydrothermal treatment of the nanocrystals to form the LDH film. The secondary grown film is found to provide a higher crystallinity and more uniform composition of metal cations in the film layer than the in situ grown film on seed-free substrate under identical hydrothermal conditions. A systematic investigation of the film evolution process reveals that the crystallite growth rate is relatively fast for the secondary grown film because of the presence of LDH nanocrystal seeds. Electrochemical performance of the resulting NiAl-LDH films as positive electrode material was further assessed as an example of their practical applications. The secondary grown film electrode delivers improved recharge-discharge capacity and cycling stability compared with that of the in situ grown film, which can be explained by the existence of a unique microstructure of the former. Our findings show an example for the effective fabrication of LDH film with controllable microstructure and enhanced application performance through a secondary (seeded) growth procedure.


Assuntos
Alumínio/química , Técnicas Eletroquímicas , Hidróxidos/síntese química , Níquel/química , Hidróxidos/química , Tamanho da Partícula , Propriedades de Superfície
15.
ACS Appl Mater Interfaces ; 7(7): 3882-7, 2015 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-25654314

RESUMO

We describe a reliable preparation of MgAl-layered double hydroxide (MgAl-LDH) micropatterned arrays on gold substrate by combining SO3(-)-terminated self-assembly monolayer and photolithography. The synthesis route is readily extended to prepare LDH arrays on the SO3(-)-terminated polymer-bonded glass substrate amenable for cell imaging. The anion-exchangeable MgAl-LDH micropattern can act both as bioadhesive region for selective cell adhesion and as nanocarrier for drug molecules to regulate cell behaviors. Quantitative analysis of cell adhesion shows that selective HepG2 cell adhesion and spreading are promoted by the micropatterned MgAl-LDH, and also suppressed by methotrexate drug released from the LDH interlayer galleries.


Assuntos
Adesão Celular/efeitos dos fármacos , Sistemas de Liberação de Medicamentos/instrumentação , Hidróxidos/química , Ânions/química , Células/citologia , Células/efeitos dos fármacos , Células Hep G2 , Humanos , Metotrexato/química , Metotrexato/farmacologia
16.
Nanoscale ; 6(1): 203-6, 2014 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-24247636

RESUMO

Development of a simple, reproducible and cost-effective protocol for mass production of non-precious-metal electrocatalysts for oxygen reduction reaction (ORR) is still challenging but highly desirable for their practical applications in industry. Herein, we developed a facile and scalable method to directly produce graphene (G) supported CoFe-LDHs and successfully used them as a precursor for mass production of Co/CoO/CoFe2O4/G as a low-cost and Pt-free efficient electrocatalyst, which exhibits comparable electrocatalytic activity and much better durability for ORR in comparison with commercial Pt/C catalysts. The result may provide a way for cost-effective production of ORR electrocatalysts on a large scale for practical applications.


Assuntos
Cobalto/química , Compostos Férricos/química , Grafite/química , Hidróxidos/química , Nanocompostos/química , Óxidos/química , Oxigênio/química , Catálise , Cátions/química , Técnicas Eletroquímicas , Platina/química
17.
J Colloid Interface Sci ; 407: 17-21, 2013 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-23899457

RESUMO

Layered double hydroxides (LDHs), also called hydrotalcites, have been widely investigated for degradation of dye molecules, in the forms of direct photocatalysts, supports or precursors to ZnO-containing photocatalysts. LDH precursor-derived ZnO/ZnAl2O4 photocatalytic nanostructures have hitherto been created, involving ZnO/ZnAl2O4 powder and templated hierarchical frameworks with laboratory-scale preparations. We herein report a scalable preparation of ZnO/ZnAl2O4 microsphere derived from ZnAl-LDH precursor spray-dried microsphere. Survey of textural properties shows that ZnO/ZnAl2O4 microspheres maintain the hierarchically spherical feature and the relatively large surface area. Photocatalytic evaluation under UV irradiation shows that the ZnO/ZnAl2O4 microspheres exhibit highly enhanced photodegradation performance to methylene blue (MB) in comparison with the commercial ZnO powder. A preferential photodegradation to methyl orange (MO) of the MO/MB mixture was also observed, which was illustrated experimentally in terms of the favorable interaction and distribution between basic MO molecules and the acidic-site ZnO/ZnAl2O4 photocatalyst. Our results may initiate large-scale production of microspheres with promising photocatalytic performances.

18.
J Nanosci Nanotechnol ; 12(3): 1892-8, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22754995

RESUMO

Layered double hydroxides (LDHs), known as a type of multifunctional anionic layered clay, typically exhibit stability and intrinsic hydrophilicity at neutral and alkaline pH. We herein report a polymer bead-templated preparation of flower-like LDH shell microspheres with the LDH platelets tuned under different aging durations and temperatures. Thickness of LDH shell walls was tuned readily by varying preparation conditions such as aging durations and temperatures. After a simple chemical surface modification using fluorine-silane molecule, the flower-like LDH nano/microspheres show the distinctly different transitions from the intrinsic hydropholicity to the superhydrophobicity at pH 2 and neutral pH. In contrast, at alkaline condition of pH 12 small flower-like spheres were formed atop of the parent microspheres, which may be argued in terms of a process of desorption of silane molecule at the alkaline condition combined with dissolution and reassembly of LDH platelets. Our finding of the superhydrophobic LDH spheres may find useful applications in chemical and biosensors against harsh acidic conditions.

19.
J Colloid Interface Sci ; 385(1): 268-73, 2012 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-22840873

RESUMO

Films of laurate (La) anion-intercalated zinc-aluminum layered double hydroxides (ZnAl-La-LDHs) with hollow hemispherical protrusions on the surface of the hybrid film have been conveniently prepared by an ion-exchange reaction of a nitrate-containing LDH film previously grown in situ on a porous anodic alumina/aluminum (PAO/Al) substrate. No template is required to form the hemispherical protrusions, thus avoiding a complicated template removal process. The dimensions, morphology, and resistance to bursting of the hollow hemispherical protrusions can be easily tuned by varying the experimental conditions such as sodium laurate concentration, reaction time, and reaction temperature. The evolution of the hollow protrusions was investigated by scanning electron microscopy (SEM), and a "bubble template-reconfiguration assembly" mechanism, in which air bubbles on the film surface act as a template, has been proposed to explain their formation. When the ion-exchange reaction was carried out on a film that had been treated by ultrasound to eliminate surface air bubbles, no hemispherical protrusions were formed, which is consistent with the proposed mechanism.


Assuntos
Hidróxido de Alumínio/química , Hidróxidos/química , Lauratos/química , Membranas Artificiais , Compostos de Zinco/química , Microscopia Eletrônica de Varredura/métodos , Porosidade
20.
Chem Commun (Camb) ; 48(3): 410-2, 2012 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-22076807

RESUMO

CoO/CoFe(2)O(4) nanocomposites, derived from scalably prepared CoFe-layered double hydroxide (CoFe-LDH) single-resource precursors, exhibit tunable cycle performances and rate capabilities, which are supported by the homogenous dispersion of bi-component active CoO and CoFe(2)O(4) phases.

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