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Flower-like copper foam Co3O4 catalysts (Co3O4/CF) were prepared by hydrothermal method. The crystalline structure and microscopic morphology of the prepared samples were characterized by using X-ray diffractometer (XRD) and scanning electron microscope (SEM), and the electrochemical properties were investigated by an electrochemical workstation. The experimental results show that the Co3O4 catalysts are successfully prepared on the foamed copper support by hydrothermal method, and the material's morphology is mainly flower cluster. When the current density is 10 mA·cm−2, the overpotential value of the Co3O4/CF catalyst is 141 mV, lower than that of blank support. The electrochemical impedance (EIS) spectrum shows that the Rct value of the Co3O4/CF catalyst decreases, and the Coulomb curves of double-layer show that the electrochemically active area of the Co3O4/CF catalyst efficiently increases compared with that of the blank support. Therefore, the as-obtained Co3O4/CF catalyst exhibits a good hydrogen evolution rate, showing great applicability potential in the catalytic electrolysis of water for hydrogen production. [ABSTRACT FROM AUTHOR]

In this article, Co-doped Na3V2-xTix(PO4)2F3(NVTPF x = 0, 0.1, 0.5, 0.7) sodium ion battery anode material was prepared by one-step hydrothermal method and it was coated with graphene. The crystal structure and morphology of NVTPF cathode material were characterized by scanning electron microscope and X-ray diffractometer. The results show that the particle diameter of the sample becomes smaller and the shape gradually becomes regular with the increase of Ti doping amount. The graphene coating did not change the crystal structure of NVTPF, but it was helpful to improve its electrochemical performance. The substitution of Ti4+ for V3+ contributes to improve the electronic conductivity and diffusion coefficient of sodium ions, reduce the charge transfer impedance, and accelerate the reaction kinetics of NVTPF electrode, thus significantly improving the cycling stability of NVTPF electrode. Among the four groups of materials, Na3v1.5Ti0.5(PO4)2F3 has the best electrochemical performance. At 1C, the specific capacity of initial discharge is 53.4 mAh/g, and the capacity retention rate of 35 cycles is 72.3%. The graphene coated NVTPF has a discharge capacity of 125.9mAh/g for the first cycle and 44.8mAh/g for 35 cycles at 1C. [ABSTRACT FROM AUTHOR]

NaY(WO4)2:Yb3+/Er3+ upconversion phosphors with different Yb3+/Er3+ doping concentrations were synthesized by high temperature solid-state reaction at 1200 °C for 4 h. The phase structure, surface morphology and luminescent properties were characterized by X-ray diffraction, scanning electron microscope and fluorescence spectroscopy. The sample composed of 7% Yb3+ and 2.5% Er3+ has the best luminescent properties. At 980 nm excitation, the emission peak of all the samples locates at the green area. The energy transfer of Yb3+→Er3+ is dominant in the energy transfer. The results demonstrate NaY(WO4)2:Yb3+/Er3+ can be used as the feasible materials for biomarkers and upconversion white light-emitting diodes. [ABSTRACT FROM AUTHOR]

Using CaCO3, Sc2O3, and CeO2 as raw materials, we prepared the CaSc2O4:Ce3+ green phosphors for white light LEDs via a high-temperature solid-phase method in a reducing atmosphere. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), fluorescence spectroscopy and other means were used to characterize the phase structure, apparent morphology, and photoluminescence properties of the product. CaSc2O4 was synthesized under a reducing atmosphere (95% N2+5% H2) at 1 400 °C for 4 hours. Upon excitation with a blue light (450 nm wavelength), CaSc2O4:Ce3+ displays a broadband green emission peak at 525 nm. The color coordinates of CaSc2O4:7% Ce3+ emission peak are (0.3712, 0.5940), and the product morphology is 1 μm granular. Hence, it acts as a green phosphor suitable for white LEDs that can be excited by blue light. [ABSTRACT FROM AUTHOR]

In this paper, Co-doped Na3V2−xCox(PO4)2F3(x = 0,0.1,0.5,0.7) sodium ion battery anode material was prepared by one-step hydrothermal method, and Na3V1.5Co0.5(PO4)2F3 anode material coated with graphene was also prepared. It is confirmed that moderate Co2+ doping can improve the electrochemical performance of NVPF. Among all samples, Na3V1.5Co0.5(PO4)2F3@Graphene shows the best rate and cycle performance. It exhibits the highest specific capacity of 91.5 and 48.8 mAh/g at 1C, respectively when x = 0.5, after coating graphene, the charge-discharge specific capacities of 1C cycle are 128.2 mAh/g and 63.5 mAh/g for the first time, and 62.2 mAh/g and 45.1 mAh/g for 45 weeks.The performance results show that the excellent electrochemical performance of Na3V1.5Co0.5(PO4)2F3@Graphene can be attributed to the increase in electronic conductivity and ion diffusion coefficient. [ABSTRACT FROM AUTHOR]

A series of xPr3+ (x = 0.02, 0.04, 0.06, 0.08 and 0.10) doped Lu2MoO6 and Y2MoO6 were synthesized using high temperature solid-state reaction at 1200 °C for 4 h. X-ray diffraction, photoluminescence (PL) spectrometer, scanning electron microscopy, energy dispersive spectrometer and mapping were used to characterize the phase identification, luminescent properties, surface morphology and elemental analysis of the samples. The results show that: the doping of Pr3+ does not change the monoclinic system of Lu2MoO6 and Y2MoO6, both of which are pure phases. Lu2MoO6 and Y2MoO6 that doped 0.08 mol Pr3+ all show the best luminescence performance. Lu2MoO6: Pr3+ and Y2MoO6: Pr3+ phosphors can be excited by blue light to produce reddish yellow light. Lu2MoO6: 0.08Pr3+ phosphor emits warm reddish yellow light with the CIE coordinates of (0.4638, 0.4905), the CCT value of 3185 K and the emission lifetimes is 34.8 µs, higher than previous reports. The Y2MoO6: 0.08Pr3+ phosphor is reported for the first time to emit warm reddish yellow light with the CIE coordinates of (0.4657, 0.4983), the CCT value of 3160 K and the emission lifetimes is 112.4 µs. The present results demonstrate that Lu2MoO6: Pr3+ and Y2MoO6: Pr3+ phosphors may be a promising candidate for white light-emitting diodes. [ABSTRACT FROM AUTHOR]