分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-08-18
摘要： We present a novel strategy for simultaneous doping of Cu ions into TiO2 nanocrystals and transforming amorphous anodic TiO2 nanotubes (TNTs) into anatase nanoparticle (NP) array film. Highly reactive colloidal Cu clusters derived by laser ablation in liquids were used as doping precursor, which can react with amorphous TiO2 nanotubes to form doped anatase NPs by dissolution and recrystallization processes. The Cu-doped TiO2 NPs (Cu-TNPs) film was characterized by X-ray diffraction, scanning and transmission electron microscopy and Raman spectroscopy. The Cu-TNPs show a rugby-like shape with exposed active {101}, {001} facets and the long-axis parallel to [001] lattice direction. The substitutional Cu2+ ions dopants in TiO2 nanocrystals caused the swelling of the crystalline unit cell, red shift of the absorption edge, and enhanced absorption in the visible-light region. The green and efficient doping design would facilliate the ongoing effort toward improving nanostructured TiO2 as a practical biosensor for glucose molecules.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-08-18
摘要： We report the coexistence of resistance switching (RS) behavior and negative differential resistance (NDR) phenomenon in α-Fe2O3 nanorod film grown in situ on fluorine-doped tin oxide glass substrate. The reversible switching of the low- and high-resistance states (LRS and HRS, respectively) of the film device can be excited simply by applying bias voltage. The switching from HRS to LRS was initiated at the negative bias region, whereas the NDR process followed by the reversion of HRS occurred at the positive bias region. With the increase in compliant current (CC), the carrier conduction models of LRS and HRS both changed and the current–voltage (I–V) relationships at the NDR region were seriously affected by the thermal process according to the level of applied CC. The co-existence of RS and NDR was possibly caused by defects during migration, such as oxygen vacancies and interstitial iron ions, which were formed in the α-Fe2O3 nanorod film. This work provided information on the ongoing effort toward developing novel electrical features of advanced transition metal oxide devices.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-08-18
摘要： Incorporating noble metal nanoparticles on the surface or inner side of semiconductors to form a hybrid nanostructure is an effective route to improve the gas sensing performance of these semiconductors. In this study, we present novel Au-decorated ZnO nanospheres (Au-ZnO NSs) obtained by laser irradiation of liquids. Structural characterization indicated that the Au-ZnO NSs consisted of single crystalline ZnO NSs with few Au nanoparticles decorated on their surfaces and abundant encapsulated Au nanoparticles with relatively small sizes. Laser irradiation-induced heating–melting–evaporating processes are responsible for the formation of unique Au-ZnO NSs. Gas sensing properties of the Au-ZnO NSs, as gas sensing materials, were investigated and compared with those of pure ZnO NSs. The former showed lower working temperature, higher sensitivity, better selectivity, and good reproducibility. The response values of Au-ZnO NSs and pure ZnO NSs sensors to ethanol of 100 ppm were 252 and 75 at working temperature of 320 °C and 360 °C, respectively. The significant enhancements in gas sensing performance should be attributed to the electronic sensitization induced by the depleted layers between encapsulated Au nanoparticles and ZnO and chemical sensitization originating from the catalytic effects of Au nanoparticles decorated on the surfaces that dissociated molecular oxygen.
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