Electrodeposition of Pd-Pt Nanocomposites on Porous GaN for Electrochemical Nitrite Sensing.

In recent years, nitrite pollution has become a subject of great concern for human lives, involving a number of fields, such as environment, food industry and biological process. However, the effective detection of nitrite is an instant demand as well as an unprecedented challenge. Here, a novel nitrite sensor was fabricated by electrochemical deposition of palladium and platinum (Pd-Pt) nanocomposites on porous gallium nitride (PGaN). The obtained Pd-Pt/PGaN sensor provides abundant electrocatalytic sites, endowing it with excellent performances for nitrite detection. The sensor also shows a low detection limit of 0.95 µM, superior linear ampere response and high sensitivity (150 µA/mM for 1 to 300 µM and 73 µA/mM for 300 to 3000 µM) for nitrite. In addition, the Pd-Pt/PGaN sensor was applied and evaluated in the determination of nitrite from the real environmental samples. The experimental results demonstrate that the sensor has good reproducibility and long-term stability. It provides a practical way for rapidly and effectively monitoring nitrite content in the practical application.

Capped Polyoxometalate Pillars between Metal-Organic Layers for Transferring a Supramolecular Structure into a Covalent 3D Framework.

Two robust metal-organic frameworks (MOFs), {H4[Ni(π-H2O)2]2[Ni(rt-H2O)2]8Ni4(Tri)24}[VIVW12O40]2·24H2O (1) and {H[Ni(π-O)2]2[Ni(rt-H2O)2]8Ni4(Tri)24}[VIVW10VV2O40V2][VIVW9VV3O40VIV2]·24H2O (2) (Tri = 1,2,4-triazole), composed of polyoxometalates (POMs) and metal-organic units, were designed and synthesized by a hydrothermal method. Structure analysis indicates that there is a metal-organic crown [{Ni3(Tri)6(H2O)4}4] ({Ni12}) in these two compounds. In 1, the {Ni12} crown embraces four pendant Tri ligands that could capture a cationic [Ni(H2O)2]2+ group, resulting in the Ni13-Tri building unit [Ni(H2O)2{Ni3(Tri)6(H2O)4}4] ({Ni13}). The {Ni13} building unit was fused together by Tri bridges into the 2D metal-organic layers, which are pillared by a typical Keggin-type POM [VW12O40]4- to construct a 3D supramolecular framework via the hydrogen bonds. Interestingly, the 2D metal-organic layer in 1 was successfully transferred into a 3D covalent MOF via extension of the length of the pillars by capping a Keggin-type POM with V-O units. Moreover, electrochemical behaviors and electrocatalytic properties of these two compounds were both studied, which can act as bifunctional electrocatalysts toward the reduction of H2O2 and oxidation of nitrite in neutral aqueous solution.

Wearable Wide-Range Strain Sensors Based on Ionic Liquids and Monitoring of Human Activities.

Wearable sensors for detection of human activities have encouraged the development of highly elastic sensors. In particular, to capture subtle and large-scale body motion, stretchable and wide-range strain sensors are highly desired, but still a challenge. Herein, a highly stretchable and transparent stain sensor based on ionic liquids and elastic polymer has been developed. The as-obtained sensor exhibits impressive stretchability with wide-range strain (from 0.1% to 400%), good bending properties and high sensitivity, whose gauge factor can reach 7.9. Importantly, the sensors show excellent biological compatibility and succeed in monitoring the diverse human activities ranging from the complex large-scale multidimensional motions to subtle signals, including wrist, finger and elbow joint bending, finger touch, breath, speech, swallow behavior and pulse wave.

Correction: Large-size nanosheets of 9,10-bis(phenylethynyl)anthracene with high photoresponse and light emission anisotropy.

Correction for 'Large-size nanosheets of 9,10-bis(phenylethynyl)anthracene with high photoresponse and light emission anisotropy' by Juan-Ye Wang et al., Phys. Chem. Chem. Phys., 2016, DOI: 10.1039/c5cp05507e.

Large-size nanosheets of 9,10-bis(phenylethynyl)anthracene with high photoresponse and light emission anisotropy.

Large-size single crystalline nanosheets of 9,10-bis(phenylethynyl)-anthracene were prepared by a facile solution process and were fully characterized. The prototype photodetector was then fabricated on the basis of a single nanosheet and exhibited superior performance with the largest photoresponse ratio up to ca. 10(5). Moreover, the nanosheets show obvious light emission anisotropy.

Design and synthesis of purely inorganic 3D frameworks composed of reduced vanadium clusters and manganese linkers.

Two purely inorganic three-dimensional (3D) frameworks [Mn4(H2O)11V(IV)(18)O42(PO4)](7-) (1) and [Mn2(H2O)7V(IV)(18)O42(PO4)](11-) (2) were synthesized under hydrothermal conditions and fully characterized by single-crystal X-ray structural analysis, IR spectroscopy, thermogravimetric analysis and PXRD. Structural analysis revealed that these two compounds contained a similar all reduced polyoxoanion [V(IV)(18)O42(PO4)](15-) linked by different amounts of manganese centers to form 3D framework materials. The V centers in these two compounds were all reduced to the +IV oxidation state, resulting in an all reduced polyoxoanion, which was firstly used as the building block for constructing 3D framework materials. The all reduced typical polyoxoanion [V(IV)(18)O42(PO4)](15-) with 15 negative charges supplied enough charge amount to accept TM cations. In these two structures, the anions were surrounded by 12 and 5 Mn(2+) ions, respectively, adjusted by varying the feeding amount of MnCl2·4H2O. An electrocatalytic study revealed that compound 1 exhibits electrocatalytic activity for reduction of H2O2.

[The Synthesis, Luminescence and Energy Transmission of NaLa(MoO4) 2 : Eu3+/Tb3+/Tm3+ Materials].

A series of Eu3+ /Tb3+ /Tm3+ single/co-doped NaLa(MoO4)2 (NLM) phosphors have been synthesized by microemulsion-hydrothermal method. Phosphor crystal structure, morphology and luminescent properties were tested and studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectroscopy. The results show that the prepared samples are all tetragonal single crystals. By way of substitution, the sites of La3+ are replaced by Eu3+, Tb3+ and Tm3+. Morphology of the samples are tetragonal sheet structure and the size of particles is 1 - 1.5 µm. When the doping concentration of Eu3+ is 9%, NLM : 9%Eu3+ phosphor emission peak is the strongest at 616 nm, the critical transfer distance (R(c)) between Eu3+ in the NLM matrix is about 15.20 Å at this time. At the emission spectrum of NLM : 9%Eu3+, the peak at 591 nm is the magnetic dipole transition of 5D0 to 7F1 of Eu3+. The peak at 616 nm is the electric dipole transition of 5D0 to 7 F2 of Eu3+. Electric dipole transition emission intensity is about 10 times of the strength of the magnetic dipole transition. This indicates that Eu3+ is located at noninversion symmetry site. By Fixing Eu3+ (Tb3+) concentration and varying the concentration of Tb3+ (Eu3+), the energy transfer mechanism between Eu3+ and Tb3+ was studied. By adjusting the Eu3+, Tb3+ and Tm3+ doping concentrations, tunable luminescence of visible light region is implemented under the single matrix. The luminescence of NLM x%Eu3+, y%Tb3+, z%Tm3+ phosphors are translated from blue (0.205, 0.135) to pseudo-white (0.305, 0.266) under 360 nm irradiation.

[The Different Phase, Morphology Controllable Synthesis and Luminescent Properties Investigation of NaYF4: Yb, Er].

Using sodium fluoride and rare earth nitrate as raw materials and sodium citrate as surfactant, micron grade NaYF4 upconversion luminescent materials were prepared by hydrothermal method. By X-ray diffraction(XRD), scanning electron microscope(SEM) and fluorescence spectrometer, the crystal phase, morphology and luminescent characteristics of the prepared samples were investigated. The results showed that the phase of the samples could generate a transition from cubic phase to hexagonal phase by adjusting the proportion (5, 6, 7, 8, 9, 11) of NaF/RE , and the X ray diffraction peaks for the cubic and hexagonal phase of samples exactly matched with those of the standard card of PDF# 77-2042 and PDF# 16-0334, respectively. The SEM photographs showed that the crystallinity of samples was high and the dispersibility was favourable, the morphology were translated from microrods to hexagonal microplates. The samples upconversion luminescent spectra showed the intensity enhancement of red and green light emission peaks with increasement of the ratio of NaF/RE3+. The green emission peaks of samples at 520 and 539 nm corresponded to the ²H¹¹/²-4-->I15/2 and 4S3/2-->4I15/2 level transition of Er³âº ion, and the red light emission peaks of samples at 653 nm corresponded to the 4F9/2-->4I15/2 levelt ransition of Er+ ion. The chromaticity coordinate diagram exhibited that the change of the luminescent color of samples could be achieved by adjusting the ratio of NaF/RE³âº. With the increasing of NaF/RE³âº ratio, for the whole light-emitting colors of samples, the shift from yellow region to near red region could be realized. It can be concluded that through the relatively simple experimental procedure and lower cost materials, the change of phase and morphology, the moving of light-emitting color for sample NaYF4:Yb³âº, Er³âº could be well controlled only by changing the single component (NaF) molar ratio in the raw materials. The effect of phase and morphology of fluorescent materials on their upconversion luminescence has great potential applications in photonic devices and bioanalysis research.

[Morphology and Spectral Properties Study of LaCeF3:Tb Microcrystalline].

LaCeF3:Tb microcrystalline was synthesized by microemulsion method, oleic acid-assisted solvothermal method, ultrasonic-assisted solvothermal method separately. LaCeF3:Tb microcrystalline synthesized by ultrasonic-assisted solvothermal method is rarely reported. Using X-ray diffraction (XRD), scanning electron microscope (SEM), fluorescence spectroscopy (PL) method such as the crystal phase, morphology and luminescence properties of the samples have been characterized. XRD results show that the crystallization product is good, microcrystalline and standard card PDF# 38-0452 (the six-party LaCeF3) is corresponding, SEM images showing the product has uniform size and morphology, under 250 nm excitation nanoparticlesshows strong green light, the main emission peaks respectively belonged to 5D4-->7F6 (489 nm), 5D4-->7F5 (545 nm), 5D4-->7F4 (585 nm) and 5D4-->7F3 (621 nm) transition of Tb³âº. Through LaCeF3 and LaCeF3:Tb spectral studies prove the existence of the Ce-Tb energy transfer. Calculated the critical doping concentration of Tb in LaCeF3microcrystalline synthesized by different methods.

One-step fabrication of ultralong nanobelts of PI-PTCDI and their optoelectronic properties.

The ultralong nanobelts of N,N-bis-(1-propylimidazole)-3,4,9,10-perylene tetracarboxylic diimide (PI-PTCDI) were fabricated by a one-step solution process. The prototype devices based on the PI-PTCDI nanobelts exhibited excellent photodetector and photoswitching performance. The highest Ion/Ioff ratio and photoresponsivity of photodiodes could reach 240 and 5.6 mA W(-1), respectively.

[Color-tunable nano-material alpha-NaYF4 : Yb, Er, Tm prepared by microemulsion-hydrothermal method].

NaYF4 : Yb3+, Er3+, Tm3+ nanoparticles were prepared by microemulsion-hydrothermal method. Crystal phase, morphology and structure of the samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The luminescence properties were studied by up-conversional fluorescence spectroscopy. The XRD patterns of as-prepared samples were in agreement with the PDF # 77-2042 of cubic NaYF4. SEM images of the particles showed that the samples were cotton-like spherical in shape and which were assembled by smaller nano-particles. The average size was 120 nm, while the shape was regular and the particle size was homogeneous. Under the excitation of 980 nm, the as-prepared particles could emit blue (438 and 486 nm), green (523 and 539 nm) and red (650 nm) light simultaneously. It can be seen from the color coordinates figure (CIE) that when doping concentration ratio of Tm3+ and E3+ increased from 0 to 2, the whole emitting light color of samples movedto green region. While the ratio was 1 : 1, pseudo white light was obtained. As the ratio changed from 2 to 7, the luminous color was moved to red region.

[Influence of Bi3+ doping on properties of CaMoO4 : Eu3+ phosphors].

Europium doped CaMoO4 and bismuth co-doped CaMoO4 : Eu3+ phosphors were prepared via microemulsion-hydrothermal method. The structure, morphology and luminescence properties of samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectroscopy, respectively. The XRD patterns of as-prepared samples were in agreement with the PDF # 29-0351 of CaMoO4, which indicated that the phosphor possessed tetragonal crystal structure. SEM images showed that the samples were basically flake in shape and their average size was 1.5-2.5 microm. The critical molar concentration of activator (Eu3+) in CaMoO4 : Eu3+ was 5%, and the predominant peak of CaMoO4 : Eu3+ located at 616 nm, corresponding to the 5D0 -->7 F2 electronic dipole transition of Eu3+. The photoluminescence color can be tuned from orange-yellow (0.514, 0.537) to white (0.339, 0.333) by adjusting the doping concentrations of Eu3+ ions. To enhance the red emission intensity of Eu3+, Bi3+ was used to co-dope CaMoO4 : Eu3+ as sensitizers. When the concentration of Bi3+ is 3%, luminescence intensity was maximum. The chromaticity coordinates (CIE) varied from orange (0.497, 0.347) to red (0.585, 0.349) with increasing the content of Bi3+.

[Synthesis and fluorescence of KznF3 : Ce3+, Tb3+ nanoparticles].

Phosphors of KZnF3 : Ce3+, KZnF3 : Tb3+ and KZnF3 : Ce3+, Tb3+ nanoparticles were synthesized in a cetyltrimethylammonium bromide (CTAB)/2-octanol/water microemulsion system. X-ray diffraction (XRD) pattern was used to identify the formation of KZnF3 phase without detectable impurity. Environment scanning electron microscopy (ESEM) image showed that the average sizes of the KZnF3 : Ce3+ , Tb3+ nanocrystals were 30 nm in diameter. Photoluminescence characteristics of the rare earth ions doped nanoparticles were investigated and compared with that of the sample prepared by solid state reaction at a high temperature. The emission peak of the KZnF3 : Ce3+ nanoparticles showed an obvious red shift as compared to that of polycrystalline powder. In a co-doped system of KZnF3 nanoparticles, the emission band of Ce3+ even could hardly be observed and the luminescence intensity of Tb3+ was increased much compared with that Tb-doped singly. This showed that the emission of the Tb3+ was sensitized by Ce3+. The experimental results indicated that there was an effective energy transfer from Ce3+ to Tb3+ in KZnF3 nanoparticles.