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Cylindrical lab-scale tank based on compacts of Mg(NH 2 ) 2 –2LiH–0.07KOH mixed with expanded natural graphite (ENG) was designed. And the influences of ENG content and compaction pressure on the hydrogen desorption properties of the tank, including bed temperature, hydrogen flow rate and desorption capacity were investigated under the constant flow rate mode. As the ENG content increases, the heat transfer property of the hydride bed improves significantly, which results in the rise of the central temperature of the hydride bed and the increase of the hydrogen desorption time at the constant flow rate. As the compaction pressure increases, the hydrogen permeability of the hydride bed decreases obviously, but the entire desorption process changes a little. The results indicate that the heat transfer behavior of the hydride bed dominates the hydrogen desorption process of the tank. [ABSTRACT FROM AUTHOR]

(2LiNH 2 + MgH 2 ) material is one of the most promising hydrogen storage materials. In applications, CO impurity in hydrogen has an effect on the hydrogen storage performance of (2LiNH 2 + MgH 2 ) material. In this work, the effect of CO on the hydrogen storage properties of KF doped (2LiNH 2 + MgH 2 ) material was investigated by using hydrogen containing 1 mol% CO as the hydrogenation gas source. The results indicate that the hydrogen desorption capacity of the hydride decreases from 4.73 wt.% to 3.88 wt.% after 5 hydrogenation cycles. The decrease of the capacity is attributed to the permanent loss of the NH 2 caused by the formation of Li 2 CN 2 and KCN. Moreover, the hydrogen desorption kinetics declines obviously, and the dehydrogenation activation energy increases from 122.1 kJ/mol to 132.0 kJ/mol. Furthermore, it is found that the hydrogen desorption kinetics cannot be recovered to the initial level after re-milling. The main reason for these is that the catalytic effect on (Mg(NH 2 ) 2 + 2LiH + 0.05KF) system disappears due to the transformation from KH to KCN. [ABSTRACT FROM AUTHOR]

Abstract: A simple soft chemistry route was developed to synthesize nanocrystalline Li–Ni ferrite (Li0.25Ni0.5Fe2.25O4). The as-prepared ferrite samples were characterized by X-ray diffractometer (XRD), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM). The effects of the annealing temperature on the particle sizes and magnetic properties of the synthesized Li–Ni ferrites were investigated. The results indicated that the ferrite samples obtained by this method had the single-phase spinel structure. Particle sizes estimated from Scherrer''s formula increased with the annealing temperature. The magnetic properties of the ferrite samples showed strong dependence on the annealing temperature. The coercivity initially increased and then decreased with increasing annealing temperature whereas the saturation magnetization continuously increased. [Copyright &y& Elsevier]

Compared to Na 3 V 2 (PO 4) 3 , NASICON-typed Na 3+ x Mn x V 2- x (PO 4) 3 with a suitable amount of Mn substitution exhibits higher energy density and low cost due to activation of the V5+/V4+ redox reaction during the electrochemical process. However, the low electrical conductivity severely limits the cycling stability and rate capability. Herein, a combination of dual-carbon coated and Mn2+ doped Na 3.5 Mn 0.5 V 1.5 (PO 4) 3 (NMVP/C@GO) composite is reported to improve Na storage performance. The dual-carbon conductive network is favorable to electronic and ionic transportation, facilitating the kinetic characteristics and structural stability of electrodes. Consequently, the obtained NMVP/C@GO composite delivers a reversible capacity of 112 mAh g−1 at 2 C and decent capacity retention of 81.3% after 400 cycles. Moreover, it delivers an impressive rate capacity of 88 mAh g−1 at 20 C. This work provides a facile and beneficial strategy to achieve high-energy cathode of SIBs. • The combination of dual-carbon coating and Mn2+ doping improves electrochemcial performance of cathode material. • The novel cathode material Na 3.5 Mn 0.5 V 1.5 (PO 4) 3 /C@GO delivers high reversible capacity and excellent rate capacity. • Better high reversibility of V4+/V5+ redox reaction enables high initial Coulombic efficiency of 92.4%. [ABSTRACT FROM AUTHOR]

Water electrolysis to produce high-purity hydrogen has been regarded as the most promising and attractive method for renewable energy production. The intrinsic high kinetic barrier of the involved electrode reactions, especially that of the anodic oxygen evolution reaction (OER), however severely hinders the application of the water electrolysis technology for large scale hydrogen production. In this paper, a nano-composite Fe- and Co-based material containing crystalline metal sulfide ((NiFeCo)S) and amorphous metal phosphide ((FeCo)P) was in-situ grown on the surface of foam nickel (NF). The (FC)P-(NFC)S/NF catalyst exhibits ultra-high activities for OER at high current densities in 1.0 M KOH, delivering 500 and 1000 mA cm−2 at ultralow overpotentials of 274 and 280 mV, respectively with a small Tafel slope of 37.8 mV dec−1. The excellent catalytic activities of (FC)P-(NFC)S/NF far exceed those of the reference single-component (FC)P/NF and (NFC)S/NF catalysts, and also exceed those of most non-noble metal catalysts reported in literature. Besides, the (FC)P-(NFC)S/NF catalyst exhibits high stability with almost no significant activity attenuation after the chronopotentiometric test at both 100 and 500 mA cm−2 for 40 h. The synergistic effects between the metal sulfide and metal phosphide have positive impacts on the OER activity through increasing the surface area, enhancing the reactivity of each active site, improving the electrical conductivity as well as the interface between the crystalline and amorphous phases. The present work provides a new strategy to develop cost-effective and efficient electrocatalysts toward OER and water electrolysis. ● (FeCo)P-(NiFeCo)S/NF shows ultrahigh activity for OER at large current densities. ● Ultralow overpotential (η 1000 =280 mV) is needed with Tafel slope of 37.8 mV dec−1. ● The catalyst shows high stability with no activity decay after 40 h of CP test. ● The interface between crystalline and amorphous phases contributes to the catalysis. [ABSTRACT FROM AUTHOR]

Layered Li 1+ x Ni 0.5 Co 0.2 Mn 0.3 O 2 ( x = 0, 0.02, 0.04, 0.06, 0.08) materials were synthesized using the co-precipitation method. Rietveld refinements measurements reveal that the concentration of Ni 2+ -3b ions decreases from 0.06 to 0.043, with x changing from 0.02 to 0.08. The initial coulombic efficiency improves with the increase in the content of Li-excess because the content of Ni at the 3b site decreases with the increase of Li-excess in the samples from 0 to 0.08. The analysis indicates that Li 1.08 Ni 0.5 Co 0.2 Mn 0.3 O 2 exhibits the largest diffusivity value due to the dependence of the diffusion coefficient of lithium ions on the content of Ni in the 3b sites. [ABSTRACT FROM AUTHOR]

Abstract: Blue oxonitridosilicate phosphors with compositions of (Y1−x Ce x )5Si3O12N (x =0–0.1) have been synthesized. The structures, photoluminescence properties and the relations between the structure and luminescence have been investigated and discussed. The atomic positions and the lattice parameters of Y5Si3O12N were acquired. Y atoms occupy two crystallographic sites (Y(1) and Y(2)) in the structure. Ce3+ ions were substituted for Y3+ ions and two types of photoluminescence centers (Ce(1)3+ and Ce(2)3+) have been formed. The excitation and emission processes of Ce(1)3+ and Ce(2)3+ photoluminescence centers were identified and studied. The concentration- and temperature-dependent properties of these Y5Si3O12N:Ce3+ phosphors were investigated. This study shows these blue Y5Si3O12N:Ce3+ phosphors the potential applications in the three-RGB phosphor-converted white LEDs. [Copyright &y& Elsevier]