Ferric ion substitution renders cadmium metal-organic framework derivatives for modulated Li storage based on local oxidation active centers.

In this work, a novel anionic Cd-MOF ([(CH3)2NH2]n[Cd(HL)DMF]n·2nH2O·nDMF, H4L = 1,2,4,5-tetrakis[(4-carboxy)phenoxymethyl]benzene) was synthesized for the first time. As a precursor, it was utilized to obtain Fe@Cd-MOF crystals via the substitution of Fe3+ ions due to a negatively charged framework and free-coordinated carboxyl group. Fe3O4/Fe-embedded carbon-based materials (Fe@Cd-MOFD) were further constructed by deriving Fe@Cd-MOF at high temperatures. The derived Fe@Cd-MOFD showed a structure resembling a central city with metal redox centers embedded into a carbon matrix. The introduced Fe3+ ions formed a local nano-sized metal oxide upon annealing, and these derived carbon materials offered high electronic conductivity. These pushed Fe@Cd-MOFD to remarkable electrochemical performance with an initial discharge capacity of 1703.8 mA h g-1. This work offers new insights into the fabrication of novel MOF-derived iron oxide hybrids for lithium storage.

Fabrication of 3D hierarchical Fe2O3/SnO2photoanode for enhanced photoelectrochemical performance.

Exploring and fabricating a suitable photoanode with high catalytic activity is critical for enhancing photoelectrochemical (PEC) performance. Herein, a novel 3D hierarchical Fe2O3/SnO2photoanode was fabricated by a hydrothermal route, combining with an annealing process. The morphology, crystal structure were studied by scanning electron microscopy, transmission electron microscopy, x-ray photon spectroscopy, and x-ray diffraction, respectively. The results reveal the successful preparation of Fe2O3nanothorns on the surface of SnO2nanosheets. The as-fabricated 3D Fe2O3/SnO2photoanode yields obviously promoted PEC performance with a photocurrent density of approximate 5.85 mA cm-2, measured in a mixture of Na2S (0.25 M) and Na2SO3(0.35 M) aqueous solution at 1.23 V (versus reversible hydrogen electrode, RHE). This value of photocurrent is about 53 times higher than that of the bare SnO2photoanode. The obvious improved PEC properties can be attributed to the 3D Fe2O3/SnO2heterostructures that offer outstanding light harvesting ability as well as improved charge transport and separation. These results suggest that exploring a suitable 3D hierarchical photoanode is an effective approach to boost PEC performance.

Mesoporous cobalt ferrite phosphides/reduced graphene oxide as highly effective electrocatalyst for overall water splitting.

Although the electrochemical production of hydrogen has been considered as a promising strategy to obtain the sustainable resources, the sluggish kinetics of anodic oxygen evolution reaction (OER) hindered the sustainable energy development. Herein, we design mesoporous cobalt ferrite phosphides hybridized on reduced graphene oxide (rGO) as a highly efficient bifunctional catalyst through a simple nanocasting method. The hybrid catalyst possesses the abundant interface, which provides the large active sites, as well as the hybrid rGO accelerates the electron exchange and ion diffusion. Moreover, the mesoporous structure not only prevents the aggregation of actives sites, but also benefits for the rapid escape of bubbles during catalytical process, which can significantly improve the catalytic performance. Consequently, the resulting mCo0.5Fe0.5P/rGO shows superior catalytic performance with a low overpotential of 250 mV at a current density of 10 mA cm-2 for OER and outstanding long-term stability. More importantly, an electrolyzer with mCo0.5Fe0.5P/rGO as both anode and cathode catalysts shows a low voltage of 1.66 V to afford a current density of 10 mA cm-2. This work offers a new route for designing the highly efficient OER and overall water splitting electrocatalysts.

Engineering of rice varieties with enhanced resistances to both blast and bacterial blight diseases via CRISPR/Cas9.

Rice blast and bacterial blight represent two of major diseases having devastating impact on the yield of rice in most rice-growing countries. Developments of resistant cultivars are the most economic and effective strategy to control these diseases. Here, we used CRISPR/Cas9-mediated gene editing to rapidly install mutations in three known broad-spectrum blast-resistant genes, Bsr-d1, Pi21 and ERF922, in an indica thermosensitive genic male sterile (TGMS) rice line Longke638S (LK638S). We obtained transgene-free homozygous single or triple mutants in T1 generations. While all single and triple mutants showed increased resistance to rice blast compared with wild type, the erf922 mutants displayed the strongest blast resistance similar with triple mutants. Surprisingly, we found that Pi21 or ERF922 single mutants conferred enhanced resistance to most of tested bacterial blight. Both resistances in mutants were attribute to the up-regulation of SA- and JA-pathway associated genes. Moreover, phenotypic analysis of these single mutants in paddy fields revealed that there were no trade-offs between resistances and main agricultural traits. Together, our study provides a rapid and effective way to generate rice varieties with resistance to both rice blast and bacterial blight.

A highly sensitive sensor based on ordered mesoporous ZnFe2O4 for electrochemical detection of dopamine.

Accurate and sensitive detection of dopamine (DA) is fundamental to monitor and diagnose certain neurological diseases. Herein, highly ordered mesoporous ZnFe2O4 (OM-ZnFe2O4) is prepared via a facile nanocasting method and shows the highly sensitive in the electrochemical detection of DA. The optimized OM-ZnFe2O4-40 shows the most excellent activity for DA oxidation in a wide linear range from 2 to 600 nM with a quick response time of 5 s, high sensitivity of 0.094 nA nM-1 and a lower detection limit of 0.4 nM (S/N = 3). The electrode modified with OM-ZnFe2O4 is further successfully used to monitor the increase of DA concentration induced by K+-stimulation of living PC12 cells in a neurological environment. This work offers a simple and powerful strategy for designing electrodes for detecting DA in biological systems.

Effect of Pt doping on the preferred orientation enhancement in FeCo/SiO2 nanocomposite films.

We prepared FeCoPt/SiO2 thin films by sol-gel spin-coating technique. As-prepared composite films were reduced in hydrogen to induce texture growth. Structural, magnetic property and surface morphology of the films were characterized by X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and scanning electron microscope (SEM). These experimental data indicate that integrated intensity ratio I(200)/I(110) of diffraction peaks (200) and (110) of FeCo firstly increases and then decreases, while the coercivity first decreases and then increases with increasing Pt doping content. The specimen with less Pt doping content has a large I(200)/I(110) value and small coervicity value, which is closely related with strong (200) texture in FeCo thin film. These results indicate that fcc-Pt is also in favor of promoting (200) FeCo texture like Al or Cu elements, and this similar trends of Pt and Al originate from their similar atomic radius and crystal cell volume.

Ni nanoparticles supported on graphitic carbon nitride as visible light catalysts for hydrolytic dehydrogenation of ammonia borane.

The development of a robust and low-cost non-noble metal catalyst for photocatalytic H2 evolution is of great importance for practical applications. In this study, monodisperse Ni nanoparticles of controlled sizes were prepared by a facile method and anchored on graphitic carbon nitride (g-C3N4) nanosheets via a self-assembly route. The noble-metal-free Ni/g-C3N4 composite catalysts exhibit excellent photocatalytic activities for the hydrolytic dehydrogenation of ammonia borane (AB) under visible light. An optimum AB hydrolysis rate was obtained when the size of the Ni NPs was 3.2 nm, with an initial turnover frequency of 18.7 mol(hydrogen) mol(catalyst)-1 min-1 and an apparent activation energy of 36 kJ mol-1. This study provides validity for constructing high performance first-row transition metal nano-photocatalysts for the hydrolytic dehydrogenation of AB.

Study the effect of Li+ on the ν2/ν3+ν4 Fermi resonance of acetonitrile by Raman Spectroscopy.

Raman spectra of the solution of LiClO4 in acetonitrile (CH3CN) at different concentrations have been measured. With increasing the concentration of Li+, it was noted that several vibrational modes of CH3CN had significant changes in Raman shifts and some new Raman peaks emerged due to the CH3CN⋯Li+ complex formation. In addition, Fermi resonance phenomenon between the ν2' and (ν3 + ν4)' Raman bands of CH3CN⋯Li+ complex was observed. Based on the Bertran's equations, Fermi resonance parameters of free CH3CN and CH3CN⋯Li+ complex at different concentrations have been calculated, respectively. Compared the Fermi resonance coupling coefficients W of free CH3CN with CH3CN⋯Li+ complex at different concentrations, the free CH3CN had a little smaller value, which indicated that the ν2'/(ν3 + ν4)' Fermi resonance in CH3CN⋯Li+ complex was much stronger than the ν2/ν3 + ν4 Fermi resonance in CH3CN. From the detailed analysis of the effect of Li+ on the spectral features of CH3CN, the effect mechanism of Li+ coordination to CH3CN at the nitrogen of the CN group on the ν2/ν3 + ν4 Fermi resonance of CH3CN has been elucidated.

High-performance asymmetric supercapacitors based on monodisperse MnO nanocrystals with high energy densities.

Monodisperse spherical MnO nanocrystals (NCs) with a size of 22.5 nm were synthesized by the thermal decomposition of manganese oleate in the presence of oleic acid and 1-octadecene. The as-synthesized MnO NCs show superior electrochemical performances with a specific capacitance of 736.4 F g-1 at a current density of 1 A g-1 and retain 93.3% of initial specific capacitance after 5000 cycles. The MnO NC electrode was successfully assembled in an asymmetric supercapacitor as the cathode with an activated carbon (AC) electrode as the anode. The as-fabricated device can demonstrate remarkable performance with an energy density of 44.2 W h kg-1, a power density of 900 W kg-1, and excellent cycling stability. This work provides a new direction for MnO nanomaterials towards high-performance energy storage devices.

Enhanced Thermal Conductivity and Dielectric Properties of Iron Oxide/Polyethylene Nanocomposites Induced by a Magnetic Field.

Iron Oxide (Fe3O4) nanoparticles were deposited on the surface of low density polyethylene (LDPE) particles by solvothermal method. A magnetic field was introduced to the preparation of Fe3O4/LDPE composites, and the influences of the magnetic field on thermal conductivity and dielectric properties of composites were investigated systematically. The Fe3O4/LDPE composites treated by a vertical direction magnetic field exhibited a high thermal conductivity and a large dielectric constant at low filler loading. The enhancement of thermal conductivity and dielectric constant is attributed to the formation of the conductive chains of Fe3O4 in LDPE matrix under the action of the magnetic field, which can effectively enhance the heat flux and interfacial polarization of the Fe3O4/LDPE composites. Moreover, the relatively low dielectric loss and low conductivity achieved are attributed to the low volume fraction of fillers and excellent compatibility between Fe3O4 and LDPE. Of particular note is the dielectric properties of Fe3O4/LDPE composites induced by the magnetic field also retain good stability across a wide temperature range, and this contributes to the stability and lifespan of polymer capacitors. All the above-mentioned properties along with the simplicity and scalability of the preparation for the polymer nanocomposites make them promising for the electronics industry.

Graphene-copper composite with micro-layered grains and ultrahigh strength.

Graphene with ultrahigh intrinsic strength and excellent thermal physical properties has the potential to be used as the reinforcement of many kinds of composites. Here, we show that very high tensile strength can be obtained in the copper matrix composite reinforced by reduced graphene oxide (RGO) when micro-layered structure is achieved. RGO-Cu powder with micro-layered structure is fabricated from the reduction of the micro-layered graphene oxide (GO) and Cu(OH)2 composite sheets, and RGO-Cu composites are sintered by spark plasma sintering process. The tensile strength of the 5 vol.% RGO-Cu composite is as high as 608 MPa, which is more than three times higher than that of the Cu matrix. The apparent strengthening efficiency of RGO in the 2.5 vol.% RGO-Cu composite is as high as 110, even higher than that of carbon nanotube, multilayer graphene, carbon nano fiber and RGO in the copper matrix composites produced by conventional MLM method. The excellent tensile and compressive strengths, high hardness and good electrical conductivity are obtained simultaneously in the RGO-Cu composites. The results shown in the present study provide an effective method to design graphene based composites with layered structure and high performance.

Controlled synthesis and magnetic properties of iron-cobalt-phosphide nanorods.

A simple one-step solution-phase synthesis of iron-cobalt-phosphide ((Fe1-xCox)2P) nanorods (NRs) is reported in this paper. Through the control of the amount of Co in the samples, the crystal structure of (Fe1-xCox)2P NRs changes from a pure Fe-rich hexagonal Fe2P type structure to a mixture of Fe-rich hexagonal Fe2P and Co-rich orthorhombic Co2P type structures. These samples show superparamagnetic behavior at room temperature and ferromagnetic properties at 10 K. When the Co composition is 0.09, the (Fe0.91Co0.09)2P sample has the highest coercivity around 5.74 kOe at 10 K. The current route provides a new and general chemical method for tunable preparation of (Fe1-xCox)2P (x < 0.28) NRs, which are significant for the development of new iron- or cobalt-rich permanent magnet materials without rare-earth or noble metals.