Fabrication, annealing, and electrocatalytic properties of platinum nanoparticles supported on self-organized TiO_2 nanotubes

The platinum nanoparticles supported on self-organized TiO2 nanotubes （Pt-TiO2/Ti） were prepared using electrochemical anodic oxidation followed by cathodic reduction. The structure and chemical nature of the Pt-TiO2/Ti electrocatalyst were investigated by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. Both XRD and SEM results indicate the presence of platinum on nanotubular TiO2. The stability of the Pt deposits was also investigated in 0.5 mol/L H2SO4 solution by cyclic voltammetry. The electrocatalytic activity of the Pt-TiO2/Ti catalyst exhibits enhancement effect during electro-oxidation of methanol when annealed to anatase. Successive cyclic voltam- mograms of methanol oxidation on the Pt-TiO2/Ti electrocatalyst shows unique electrocatalytic characteristics when compared to methanol oxidation on the bulk Pt catalyst. This is because of further quick oxidation of adsorbed CO by Pt （111） facets of Pt particles on self-organized TiO2 nanotubes when the formation of an electroactive film onto the working catalyst surface occurs.

One-pot synthesis of Pt-Cu bimetallic nanocrystals with different structures and their enhanced electrocatalytic properties

Shape-controlled synthesis of Pt-Cu alloy nanocrystals （NCs） with unique geometries is of great importance in the rational design and deterministic synthesis of highly active electrocatalysts. Herein, Pt-Cu alloy NCs with concave octahedron （COH）, porous octahedron （POH）, yolk-shell （YSH）, and nanoflower （NOF） structures were fabricated by altering the sequential reduction kinetics in a one-pot aqueous phase. The effect of the reaction kinetics on the formation of Pt-Cu bimetallic NCs with different morphologies was analyzed quantitatively. The concentrations of glycine and metal cation are demonstrated to play a key role in the reduction of Pt（Ⅳ） and Cu（Ⅱ） ions; these significantly affected the morphology of Pt-Cu NCs. These Pt-Cu alloy NCs exhibit substantially enhanced catalytic activity and durability for methanol and formic acid oxidation compared to the commercial Pt/C catalyst. Specifically, the COH and NOF Pt-Cu NCs with more step atoms, intragranular dislocations, and protrusions showed superior electrochemical properties than those of POH and YSH Pt-Cu NCs. The structure- property relationship between the Pt-Cu NCs and their electrochemical performances was also investigated in depth.

Preparation of nanostructured mesoporous Ni Co_2O_4 and its electrocatalytic activities for water oxidation

Nanostructured mesoporous Ni Co2O4,Co3O4 and Ni O spinel oxides were prepared through the hydroxide coprecipitation method using EG（ethylene glycol） as solvent without any template.The Ni Co2O4 powders were analyzed by TGA,XRD,N2adsorption-desorption,SEM and EDS.And the electrocatalytic properties of Ni Co2O4/Ti,Co3O4/Ti and Ni O/Ti electrodes for oxygen evolution in 0.1 mol/L KOH（p H = 13）were tested by cyclic voltammetry,Tafel curves and electrolysis.The result shows that Ni Co2O4/Ti electrode has higher electrocatalytic activity in oxygen evolution reaction than Co3O4/Ti and NiO/Ti electrodes.Ni Co2O4/Ti electrode prepared at 350°C has the highest apparent current density and the highest true current density.The Tafel slope of Ni Co2O4/Ti electrode prepared at 350°C is 68.49 m V/dec.

Crystal Structure and Characterization of a Novel 2D Layered Compound Assembled from Paradodecatungstate Clusters

A novel 2D layered compound （H4HMTA）2（H3O）2{Na2（H2O）6（H2W12O42） }C12-11H2O （HMTA = hexamethylenetetraamine） has been synthesized and characterized by elemental analyses, IR, UV-Vis and X-ray diffraction. C12H74CI2N8Na2O61W12 （Mr = 3629.87） crystallizes in the triclinic system, space group P1 with a = 10.5518（2）, b = 12.1837（2）, c = 14.3088（2） A, α = 112.9470（10）, β = 93.1310（10）, γ= 106.1530（10）°, V = 1599.20（5）A3 Dc = 3.769 g.cm^-3, Z = 1, μ（MoKα） = 21.705 mm^-1, F（000） = 1634, the final R = 0.0287 and wR = 0.0686 for 5846 observed reflections with I 〉 2σ（I）. The 2D layered network is assembled from paradodecatungstate clusters linked by simple sodium-oxo bridging groups. The compound exhibits electrocatalytic activities toward both reduction and oxidation of nitrite.

Synthesis, Crystal Structure and Properties of a Copper(Ⅰ) Coordination Polymer Based on Benzimidazole Derivative

A novel copper(I) coordination polymer [C30 H18 Cu3 Cl3 N4]n was solvethermally synthesized with 1-(prop-2-en-1-yl)-2-{4-[1-(prop-2-en-1-yl)-1 H-1,3-benzodiazol-2-yl]phenyl}-1 H-1,3-benzodiazole as the flexible ligand. It crystalizes in orthorhombic system, space group Pbcn with a = 22.0890(7), b = 6.3626(2), c = 18.2480(6) ?, V = 2564.64(14) ?3 and Mr = 365.73. The compound characterized by elemental analysis, infrared spectroscopy and powder X-ray diffraction analysis displays a 2 D structure. The complex shows strong green luminescence at 506 nm and better property of electrochemical oxygen evolution.

Multifunctional V3S4-nanowire/graphene composites for high performance Li-S batteries

Lithium sulfur(Li-S)batteries have been regarded as a promising next-generation energy storage system with high theoretical specific capacity and energy density,but still facing challenges.In order to make Li-S batteries more competitive,combination of trapping sites and electrocatalytic properties for polysulfides is an effective way to improve the battery performance.In this study,we prepare a type of multifunctional V3S4-nanowire/graphene composites(V3S4-G)by uniformly dispersing V3S4 nanowires on the graphene substrate.This structure contributes to the sufficient exposure of multifunctional V3S4 active sites which can anchor polysulfides and accelerate reaction kinetics.Thus,the Li-S batteries based on the multifunctional V3S4-G sulfur cathode deliver a stable cycling performance and good rate capability.Even at sulfur loading of 3 mg cm^−2,the V3S4-G sulfur cathode possesses a low capacity decay rate of 0.186%per cycle at 0.5 C.