In this paper, we reported that oxygen vacancies could be introduced in tungsten oxide hierarchical nanostructures through air treatment at certain temperatures. The production of oxygen vacancies may be due to two mechanisms, i.e., critical phase transition and nanoscale inhomogeneous deformation, depending on the annealing temperature or time and the size of the building block. The oxygen vacancies can be introduced at 300 and 350 °C when critical phase transformation from orthorhombic WO3·0.33H2O to hexagonal WO3 takes place or 350 and 400 °C when nanoscale inhomogeneous deformation occurs in the nanobelts. Moreover, the oxygen vacancy concentration is also influenced by the annealing time. For comparison, the oxygen vacancies are also introduced by hydrogen treatment. It is found that a certain amount of oxygen vacancies introduced by air treatment could trap and transfer electrons, thus decreasing the electron–hole recombination rate and improving the conductivity, while an abundance of oxygen vacancies introduced by hydrogen treatment could facilitate the electron–hole pair recombination and destroy the hexagonal tunnel structure, resulting in lower photocatalytic activity and electrochemical performance. Through air treatment, the constant rate of photocatalytic performance in degrading rhodamine B under visible light irradiation can reach 0.0300 min–1, and the specific capacitance can improve to 166.7 F/g. It is suggested that both photocatalytic activity and electrochemical performance can be greatly improved by introducing a proper concentration of oxygen vacancies through air treatment.

Layered hydrogen titanate nanowires were synthesized from TiO2 via an alkaline−hydrothermal process and subsequent acid treatment. The average diameter of as-prepared nanowires is about 100 nm with a uniform interlayer spacing of 0.81 nm. The framework of this hydrogen titanate nanowires holds the composition of H2Ti3O7 as determined by thermogravimetric analysis. The nanostructured electrode made from these nanowires shows large lithium intercalation capacity (reversible lithium intercalation with Li0.71H2/3TiO7/3), high discharge/charge rate capability, and excellent cycling stability, as revealed by galvanostatically charge/discharge cycling tests. The detailed cyclic voltammetric investigation, however, indicates that the hydrogen titanate nanowires show pseudocapacitive characteristic during the Li+ insertion process. The novel electrochemical properties of hydrogen titanate nanowires are attributed to the open layered structure with a much larger interlayer spacing than normal intercalation compounds for commercial lithium ion batteries. The layered hydrogen titanate nanowires with unique electrochemical performance may become a promising lithium intercalation material for high-energy rechargeable lithium ion batteries and electrochemical supercapacitors.

Sr 4 Al 14 O 25 : Eu , Dy material with an extraordinarily long afterglow was synthesized via a traditional ceramic processing. Such a long afterglow observed can last over 20 h at recognizable intensity level (0.32 mcd/m2), which is attributed to energy exchange between the traps and emission states resulting from Dy and Eu doping. When the Eu2+ concentration doped in the host is less than 1.2 mol %, the emission spectra of Sr4Al14O25:Eu, Dy show two main peaks at 407 and 494 nm, ascribed to two types of Eu2+ centers existing in the Sr4Al14O25 host. The emission peak at 407 nm disappears slowly with increasing concentration of Eu2+ due to the energy exchange between two types of Eu2+ centers.

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Nanometre precursor powders of ZnO and various additives are synthesised by a new technology, namely chemical coprecipitation and plasma pyrolysis. Transmission electron microscopy (TEM) and the Brunauer-Emmett-Teller (BET) method are employed to illustrate the precursor powders' properties. The ZnO and additive composite powders are composed of spherical particles whose size is about 10-50 nm. Varistors are prepared by sintering the precursor powders at 1050°C. Scanning electron microscopy (SEM) results show that the average grain size of the varistors is about 1.0 mm. The prepared ZnO-based varistors have excellent electronic properties. Analytical results reveal that the breakdown voltage is 500.0 V mm −1 and the non-linear coefficient is about 54.0.