The exploitation of a low-cost catalyst is desirable for hydrogen generation from electrolysis or photoelectrolysis. In this study we have demonstrated that nickel phosphide (Ni12P5) nanoparticles have efficient and stable catalytic activity for the hydrogen evolution reaction. The catalytic performance of Ni12P5 nanoparticles is favorably comparable to those of recently reported efficient nonprecious catalysts. The optimal overpotential required for 20 mA/cm(2) current density is 143 ± 3 mV in acidic solution (H2SO4, 0.5 M). The catalytic activity of Ni12P5 is likely to be correlated with the charged natures of Ni and P. Ni12P5 nanoparticles were introduced to silicon nanowires, and the power conversion efficiency of the resulting composite is larger than that of silicon nanowires decorated with platinum particles. This result demonstrates the promising application potential of metal phosphide in photoelectrochemical hydrogen generation.

Cobalt phosphide (Co 2 P) nanorods are found to exhibit efficient catalytic activity in hydrogen evolution reaction (HER), with the overpotential required for the current density of 20 mA/cm 2 as small as 167 mV in acidic solution and 171 mV in basic solution. In addition, the Co 2 P nanorods can work stably in both acidic and basic solution during hydrogen production. This performance can be favorably comparable to typical high efficiently non-precious catalysts, and suggest the promising application potential of the Co 2 P nanorods in the field of hydrogen production. The HER process follows a Volmer-Heyrovsky mechanism, and the rates of the discharge step and desorption step appear to be comparable during the HER process. The similarity of charged natures of Co and P in the Co 2 P nanorods to those of the hydride-acceptor and proton-acceptor in high efficient Ni 2 P catalyst, [NiFe] hydrogenase, and its analogues implies that the HER catalytic activity of Co 2 P nanorods might be correlated with the charged natures of Co and P.

A hydrothermal route to water-stable luminescent carbon dots as nanosensors for pH and temperature, Carbon (2014), doi: http:// dx. AbstractCarbon dots (CDs) as a class of heavy-metal-free fluorescent nanomaterials has drawn increasing attention in recent years due to their high optical absorptivity, chemical stability, biocompatibility, and low toxicity. Herein, we report a facile method to prepare stable CDs by hydrothermal treatment of glucose (glc) in the presence of glutathione (GSH). With this approach, the formation and the surface passivation of CDs are carried out simultaneously, resulting in intrinsic fluorescence emission. The influence of reaction temperature, reaction time and feed ratio of GSH/glc on the photoluminescence property of CDs is studied. The as-prepared CDs are characterized by UV-Vis, photoluminescence, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and transmission electron microscope, from which their structural information and property are interpreted. Owning to their pronounced temperature dependence of the steady-state fluorescence emission spectra and pH-responsive behavior, resultant CDs could work as versatile nanothermometry devices by taking advantage of the temperature sensitivity of their emission intensity, which change considerably over the physiological temperature range (1560 ºC), as well as a sensor for pH.

The development of functional copper nanoclusters (Cu NCs) is becoming increasingly widespread in consumer technologies due to their applications in cellular imaging and catalysis. Herein, we report a simple protein-directed synthesis of stable, water-soluble and fluorescent Cu NCs, using BSA as the stabilising agent. Meanwhile, in this study, hydrazine hydrate (N₂H₄·2H₂O) was used as the reducing agent. N₂H₄·2H₂O was a mild reducing agent suggesting that all processes could be operated at room temperature. The as-prepared Cu NCs showed red fluorescence with a peaking center at 620 nm (quantum yield 4.1%). The fluorescence of the as-prepared BSA-Cu NCs was responsive to pH in that the intensity of fluorescence increased rapidly by decreasing the pH from 12 to 6. Besides, with an arresting set of features including water-dispersibility, red fluorescence, good biocompatibility, surface-bioactivity and small size, the resultant BSA-Cu NCs could be used as probes for cellular imaging and catalysis. In this study, CAL-27 cells and the reaction of oxidation of styrene are used as models to achieve fluorescence imaging and elucidate the catalytic activity of the as-prepared BSA-Cu NCs.

The use of carbon-dot-based dual-emission fluorescent nanohybrids (DEFNs) as versatile nanothermometry devices for spatially resolved temperature measurements in living cells is demonstrated. The carbon dots (CDs) are prepared in the organic phase and display tunable photoluminescence (PL) across a wide visible range by adjusting the excitation wavelengths and extend of N-doping. DEFNs are formed in a straightforward fashion from CDs (emitting blue PL) and gold nanoclusters (AuNCs, emitting red PL). The DEFNs display ideal single-excitation, dual-emission with two well-resolved, intensity-comparable fluorescence peaks, and function in optical thermometry with high reliability and accuracy by exploiting the temperature sensitivity of their fluorescence intensity ratio (blue/red). Furthermore, the DEFNs have been introduced into cells, exhibiting good biocompatibility, and have facilitated physiological temperature measurements in the range of 25-45 °C; the DEFNs can therefore function as "non-contact" tools for the accurate measurement of temperature and its gradient inside a living cell.

Although the synthesis of two-dimensional (2D) layered MoS2 nanomaterials have been developing rapidly, there are many technical issues in preparing MoS2 quantum dots (QDs) with photoluminescence property. Herein, we design a facile colloidal chemical route to prepare photoluminescent MoS2 QDs using the ammonium tetrathiomolybdate ((NH4)2MoS4) as precursors and oleyl amine as reducing agent. The optical property and structure of as-prepared MoS2 QDs are investigated systematically. Resultant MoS2 QDs exhibit fluorescence (λmax=575 nm; quantum yield, 4.4%), spherical morphology with uniform thickness of ~3 nm and excitation-dependent PL phenomenon. Moreover, resultant MoS2 QDs show size-dependent tunable photoluminescence in wide visible region. With the help of the amphiphilic compound, resultant MoS2 QDs could be transferred from organic to aqueous phase. MoS2 QDs in aqueous solution have many advantages, such as good dispersion, low toxicity and photoluminescent property which make them possess promising applications in optoelectronic and biological fields. In this study, the 293T cells are used as a model to evaluate the fluorescence imaging of MoS2 QDs. The results confirm fluorescent signal appears in cytoplasm which demonstrates asprepared MoS2 QDs could be used as a probe for real-time optical cellular imaging.

A thorough understanding of the effect of N doping on the oxygen evolution reaction (OER) is greatly significant for constructing next-generation electrocatalysts with an optimal configuration and high efficiency for the fuel cell. Herein, we reported the synthesis of N-doped CoS2 through a facile method using ammonium hydroxide as the N source, the subjection of N-doped CoS2 as efficient electrocatalysts for OER, and the identification of intrinsic activities by exploring the composition and electronic configurations and their correlations with the electrochemical performance. The DFT studies evidenced that N doping could alter the electronic density of the adjacent Co atoms and thus form well-defined electronic configurations for adsorption of intermediates. Specifically, the N-enriched CoS2 afford a small overpotential of 240 mV at the current density of 10 mA cm–2 and long-term durability, endowing these N-doped materials to be ideal (but not limited to) OER electrocatalysts.

The discovery of nonlinear optical (NLO) materials for generating coherent mid-infrared (mid-IR) light is critically important in developing laser technologies. However, all of the commercialized mid-IR crystals thus far possess problems that have hindered their application. We report herein a function-directing structural design strategy to afford a new type of mid-IR NLO material, using fluorinated 5d0-transition metal octahedra to construct a polar noncentrosymmetric material K5(W3O9F4)­(IO3). The Λ-shaped [W3O12F4]10– polyanion, consisting of distorted octahedra, not only guides the alignment of the [IO3]− units but also serves as a new kind of NLO-active chromophore in the mid-IR, with K5(W3O9F4)­(IO3) possessing an optimal combination of large second-harmonic generation response (11 × KH2PO4@1064 nm and 0.5 × AgGaS2@2100 nm), wide visible and mid-IR transparency (0.32–10.5 μm), and a giant laser damage threshold (95 × AgGaS2). The important role of the [W3O12F4]10– polyanion in improving the NLO properties and extending the IR transparency region has been clarified through first-principles calculations. Our results suggest that the incorporation of fluorinated 5d0-transition metal chromophores into iodate materials may afford a viable route to novel promising mid-IR NLO materials with exceptional NLO functions.