Tingxia Wang

Enhanced electrocatalytic oxygen evolution of α-Co(OH)2 nanosheets on carbon nanotube/polyimide films

The future of energy supply depends on innovative breakthroughs in the development of highly efficient, sustainable and low-cost systems for renewable energy conversion and storage. Water splitting is a promising and appealing solution. In this work, we report Co(OH)2 on the carbon nanotube/polyimide film (PI/CNT-Co(OH)2) as an efficient electrocatalyst for the oxygen evolution reaction (OER). The PI/CNT film allows intimate growth of Co(OH)2 nanosheets on its surface. The nanosheet structure of Co(OH)2 and the underlying PI/CNT film facilitate the good OER performance of the PI/CNT-Co(OH)2 film. Co(OH)2 nanosheets on the PI/CNT film afford an earlier onset of oxygen evolution, a low overpotential of 317 mV and a small Tafel slope of 49 mV per decade in alkaline media. This work applies the PI/CNT film in water splitting to enhance the OER electrocatalytic activity of Co(OH)2, which opens up a promising avenue for the exploration of highly active electrocatalysts that can replace noble-metal based catalysts for the OER.

Study of the Quenched Defects in TiAl Alloy by Positron Annihilation

The recovery behavior of quenched-in defects in TiAl alloys was studied by positron annihilation lifetime measurements. The results indicate that there is a certain number of grain boundaries in fully annealed TiAl samples, and after being quenched, the samples contain quite a lot of secondary defects such as vacancy clusters besides a large amount of mono-vacancies. The vacancy clusters aggregate further in the temperature range from 300 to 600 degrees C due to the impurity atoms.

Photo- and Cathodoluminescence of Combustion-Synthesized Al2O3–TiC Composites

Photoluminescence and cathodoluminescence spectra of combustion-synthesized Al 2 O 3 -TiC ceramic composites were investigated. At room temperature, these composites stimulated by a 514.5 nm Ar + laser and by an electron beam with energy of 25 keV emit red light of 610 to 804 nm centered at about 696 nm and four visible bands centered at 360, 420, 570, and 700 nm, respectively. Secondary electron images, panchromatic and monochromatic CL images, and micro-elemental analyses by SEM and EPMA revealed that the luminary is corundum involving TiC, The 700 nm band of CL or PL is attributed to the transition between T 1 (et) and 3 T 2 (et) excited states, and the 570, 420, and 360 nm bands of CL to the transitions between 3 T 1 (et) or 3 A 2 (e 2 ), 1 T 1 (et), 1 E(e 2 ) excited states and 3 T 1 (t 2 ) ground state of Ti 2+ in corundum, respectively.

Cathodoluminescence of combustion-synthesized Al2O3-TiC ceramics

Al2O3-TiC ceramics are generally used as cutting tools and tape heads because of their high wear resistance, strength, fracture toughness, and good electrical conductivity [1 – 4]. Up to now, less attention has been paid to their optical properties and applications. In this paper, we report results on cathodoluminescence of Al2O3TiC ceramics combustion-synthesized from titania, aluminum and graphite powders by aluminothermic reactions. The combustion synthesis reaction can be described as follows:

Synthesis and structural characterization of gadolinium—calcium ferrites Gd1-xCaxFeO3-y (0≤x≤23)

Abstract Samples of gadolinium-calcium ferrites Gd1−xCaxFeO3− y, with x ranging from 0 to 2 3 were synthesized in air by solid state reaction. The X-ray powder diffraction studies reveal that the produced samples are one-phased orthorhombic perovskite compounds having the space group D2h16-Pbnm. The lattice constants of the Gd1− xCaxFeO3−y, samples have been determined by Cohens least-squares method. The variation of the lattice constants with x is presented. The initial substitution of Ca for Gd gives rise to a decrease of the lattice constants. Further substitution of Ca for Gd has little influence on the lattice dimensions.

Synthesis and x-ray diffraction studies of dysprosium-calcium ferrites Dy1−xCaxFeO3−y (0≤ x ≤ 23

Abstract Samples of dysprosium-calcium ferrites Dy1−xCaxFeO3−x with x ranging from 0 to 2 3 were novelly prepared in air by solid state reaction and characterized by X-ray powder diffraction. These samples are single-phased orthorhombic perovskite-type compounds belonging to the space group D2h16-Pbnm. The lattice constants of the Dy1−xCaxFeO3−x samples have been refined by Cohens least-squares method. The initial substitution of Ca for Dy leads to a decrease of the lattice constants. Further substitution of Ca for Dy has hardly any influence on the lattice dimensions.