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A facile and green microbial method to produce graphite oxide nanosheets and nanoparticles is described. The obtained graphite oxide nanosheets have few layers with 0.7-1.5 nm height and 50-300 nm size. The carbon nanoparticles possess the size of 20-60 nm and the height of 2-4 nm.

Nb2O5@carbon/reduced graphene oxide (M-Nb2O5@C/rGO) composites are fabricated by annealing the precursor of graphene oxide supported Nb-based metal organic frameworks for the first time. The lithium ion capacitor using M-Nb2O5@C/rGO as the anode and activated carbon as the cathode delivers a high energy density of 71.5 W h kg−1 and excellent cycling stability. [ABSTRACT FROM AUTHOR]

The physicochemical property of chemically prepared graphene can be significantly changed due to the incorporating of heteroatoms into graphene. In this article, boron-doped graphene sheets are used as carbon substrates instead of graphene for loading polyaniline by in situ polymerization. Compared with the individual component and polyaniline/non-doped graphene, the sandwich-like polyaniline/boron-doped graphene exhibits remarkably enhanced electrochemical specific capacitance in both acid and alkaline electrolytes. In a three-electrode configuration, the hybrid has a specific capacitance about 406 F g −1 in 1 M H 2 SO 4 and 318 F g −1 in 6 M KOH at 1 mV s −1 . In the two-electrode system of a symmetric supercapacitor, this hybrid achieves a specific capacitance about 241 and 189 F g −1 at 0.5 A g −1 with a specific energy density around 19.9 and 30.1 Wh kg −1 , in the acid and alkaline electrolytes, respectively. The as-obtained polyaniline/boron-doped graphene hybrid shows good rate performance. Notably, the obtained electrode materials exhibit long cycle stability in both acid and alkaline electrolytes (∼100% and 83% after 5000 cycles, respectively). The improved electrochemical performance of the hybrid is mainly attributed to the introduction of additional p -type carriers in carbon systems by boron-doping and the well combination of pseudocapacitive conducting polyaniline. [ABSTRACT FROM AUTHOR]

Abstract: To improve the electrochemical properties of chemically synthesized graphene hybrids, nitrogen-doped (N-doped) graphene decorated with M(OH) x (M=FeO, Ni, Co) nanoparticles were fabricated by a one-pot method at a mild temperature (95°C). Urea plays an important role in the synthesis process; it not only acts as the reducing agent and doping agent for N-doped graphene, but also as a hydroxyl donor for the fabrication of metal hydroxides and oxide-hydroxide. With the help of N-doped graphene and urea, FeOOH nanorods, Co(OH)2 nanowires and flower-like Ni(OH)2 nanoparticles were grown on the graphene sheets. The N-doped graphene hybrids exhibited the significantly improved electrochemical performances compared to the undoped equivalents or the separate components. [Copyright &y& Elsevier]

A dual-doping strategy was applied to fabricate the novel electrode materials. For the first time, the spinel hybrids of nanosized Ni x Co 1−x Fe 2 O 4 with N-doped graphene (N x -NG) were synthesized by a hydrothermal co-precipitation method. The size of Ni x Co 1−x Fe 2 O 4 (N x) nanoparticles on N-doped graphene can be tuned with the regulation of Ni/Co content. Among these nanocomposites, the Ni 0.4 Co 0.6 Fe 2 O 4 nanoparticles with the smallest average size of 10 nm are uniformly anchored on the N-doped graphene. The electrochemical characterizations display that the N 0.4 -NG exhibits the best electrochemical lithium storage performance compared to other five nanocomposites. It delivers a high capacity of 1367.0 mA h g−1 at the first discharge process，and the reversible capacity retention of 87% (2nd to 50th) at 0.1 A g−1. The excellent electrochemical performance of N 0.4 -NG can be owing to the small size of nanoparticles and its well-combination with N-doped graphene, which provide the large surface area and promote the ion/electron transfer rate. The synergistic effect resulted from the strong interaction between N 0.4 and N-doped graphene is contributed to the enhanced electrochemical performance of N 0.4 -NG. This study not only extends graphene-based electrode materials for lithium ion battery, but also promotes the development of energy resources. Unlabelled Image • A spinel hybrid of nanosized Ni x Co 1-x Fe 2 O 4 with N-doped graphene was fabricated. • Size of Ni x Co 1−x Fe 2 O 4 nanoparticles was tuned with the regulation of Ni/Co content. • A reversible capacity of 785.2 mA h g−1 of N 0.4 -NG after 50 cycles was obtained. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fluorescent quantitative detection of Cu2+ realized by L-cysteine modified ZnS. • The formation of ground state complexes is verified by experiments and simulations. • Fluorescence quenching mechanism of the probe by Cu2+ revealed by simulation. L-cysteine (L-Cys) capped ZnS fluorescent probe (L-ZnS) were synthesized by binding ZnS nanoparticles in situ with L-Cys, the fluorescence intensity of L-ZnS increased more than 3.5 times than that of ZnS due to the cleavage of S–H bonds and the formation of Zn–S bonds between the thiol group of L-Cys and ZnS. The addition of copper ions (Cu2+) can effectively quench the fluorescence of L-ZnS to realize the rapid detection of trace Cu2+. The L-ZnS showed high sensitivity and selectivity to Cu2+. The LOD (limit of detection) of Cu2+ was as low as 7.28 nM and linearity in the concentration range of 3.5–25.5 μM. Meanwhile, for the first time, electron localization function (ELF), bond order density (BOD), and natural adaptive orbital (NAdO) analysis in the Multiwfn wavefunction program based on density functional theory were carried out to probe the binding sites and binding mode of L-Cys with Cu2+, it indicated that the deprotonated carboxyl oxygen atoms of L-Cys had the lowest electrostatic potential (ESP) and provided lone pair electrons to coordinate with Cu2+ to form non-luminescent ground state complexes, which led to fluorescence quenching of L-ZnS. From the microscopic point of view of atoms, the mechanism of fluorescence enhancement of L-Cys capped ZnS and the mechanism of fluorescence quenching after adding Cu2+ were revealed in depth, the theoretical analysis results were accordance with the experiments. [ABSTRACT FROM AUTHOR]

Rhodamine B (RhB) is a kind of basic dye that is harmful to human health. Because RhB is cheap and abundant, it is easy to add it illegally to foods as a colorant. This paper used surface-enhanced Raman spectroscopy (SERS) and core-shell satellite structure Ag@SiO2-Au nanoparticles to detect RhB. We used the prepared Ag@SiO 2 -Au nanoparticles as SERS substrate to detect the ethanol solution of RhB. The silica shell protected Ag from oxidation and agglomeration and provided a large specific surface area for modified Au nanoparticles. The "hot spots" generated between metal nanoparticles can significantly enhance the Raman intensity of RhB. At the excitation wavelength of 532 nm, the SERS intensity of RhB at 1647 cm−1 has a linear relationship with the logarithm of RhB concentration in the range of 10−4-10−7 M and the limit of detection (LOD) can reach 5 × 10−9 M. Experiments verified the uniformity and stability of SERS substrate, ideal intensity can still obtain after SERS substrate stored for four weeks. Finally, we confirmed the reusability of the SERS substrate. After washing with anhydrous ethanol, the reused SERS substrate still had an enhanced effect on RhB. The prepared substrate can be used to detect actual samples with satisfactory recovery. The above results showed that Ag@SiO 2 -Au NPs could use as a sensitive, uniform, stable, and low-cost SERS substrate to detect trace RhB. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: In situ deposition of platinum (Pt) nanoparticles on bacterial cellulose membranes (BC) for a fuel cell application was studied. The platinum/bacterial cellulose (Pt/BC) membranes under different experimental conditions were characterized by using SEM (scanning electron microscopy), TEM (transmission electron microscopy), EDS (energy dispersive spectroscopy), XRD (X-ray diffractometry) and TG (thermo-gravimetric analysis) techniques. TEM images and XRD patterns both lead to the observation of spherical metallic platinum nanoparticles with mean diameter of 3–4nm well impregnated into the BC fibrils. TG curves revealed these Pt/BC composite materials had the high thermal stability. The electrosorption of hydrogen was investigated by CV (cyclic voltammetry). It was found that Pt/BC catalysts have high electrocatalytic activity in the hydrogen oxidation reaction. The single cell performance of Pt/BC was tested at 20°C, 30°C, and 40°C under non-humidified conditions. Preliminary tests on a single cell indicate that renewable BC is a good prospect to be explored as membrane in fuel cell field [B.R. Evans, H.M. O’Neill, V.P. Malyvanh, I. Lee, J. Woodward, Biosens. Bioelectron. 18 (2003) 917]. [Copyright &y& Elsevier]

• HOPC/Fe 2 O 3 is synthesized as a highly active catalyst for AP thermal decomposition. • Fe 2 O 3 nanoparticles are in-situ entrapped inside 3D HOPC with high dispersion. • AP is homogeneously confined into HOPC/Fe 2 O 3 as nanocrystals to form nanocomposites. • HOPC/Fe 2 O 3 can significantly reduce HTD temperature and increase heat releases of AP. • High activity owns to the synergistic effect between 3D HOPC and Fe 2 O 3 nanoparticles. Highly active catalyst with excellent ability to reduce the high-temperature decomposition (HTD) temperature and increase the apparent specific heat releases of ammonium perchlorate (AP) is an urgent requirement for the development of composite solid propellants. To this end, three-dimensional hierarchically ordered porous carbon (3D HOPC)/Fe 2 O 3 composite scaffolds with high BET surface area (964–1697 m2/g) and large pore volume (1.40–2.36 cm3/g) are synthesized for higher catalytic activity. The entrapment of Fe 2 O 3 nanoparticles (3.8–10.6 nm) inside 3D HOPC ensures their high dispersion and stability during the catalysis, and their size and content are readily tunable by adjusting the iron source concentration. The catalytic activity of HOPC/Fe 2 O 3 composite scaffolds is investigated through synthesizing AP/HOPC/Fe 2 O 3 nanocomposites, in which AP nanocrystals are homogeneously confined. Owing to the synergistic effect between 3D HOPC and Fe 2 O 3 nanoparticles, HOPC/Fe 2 O 3 composite scaffolds exhibit outstanding catalytic activity for AP thermal decomposition in decreasing the HTD peak temperature from 440.9 to 280.5 °C, lowering the activation energy from 176.4 to 132.2 kJ/mol, and increasing the heat release from 371 to 2114 J/g. This work constructs a highly active catalyst configuration by entrapping nano transition metal oxides inside carbon scaffolds, which has broad application prospects in AP-based composite solid propellants. [ABSTRACT FROM AUTHOR]

In this work, lanthanum tungstate (La 2 (WO 4) 3) nanoparticles (NPs) were synthesized by facile sonochemical method (elmasonic P, under-sonication 37/100 kHz, ~60 W energy) and utilized as an electrode material for the selective and sensitive electrochemical determination of anti-scald inhibitor diphenylamine (DPA). The synthesized La 2 (WO 4) 3 NPs were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDAX), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) analyses. The results revealed that the sonochemically synthesized La 2 (WO 4) 3 nanoparticles were with high crystallinity and uniformly distributed nanoparticles like structure. The as-prepared lanthanum tungstate NPs exhibited an excellent electrocatalytic behavior for DPA determination with the lowest detection limit of 0.0024 µM, wide linear range response of 0.01–58.06 µM and a remarkable sensitivity of 1.021 µA µM−1 cm−2. Furthermore, La 2 (WO 4) 3 NPs showed a good recovery to DPA in apple juice sample. Besides, the electrochemical mechanism of the DPA oxidation reaction was provided in detail. [ABSTRACT FROM AUTHOR]