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The pristine and Cr-doped ZnO nanorods were successfully synthesized via a facile hydrothermal route. We found that the ethanol gas response of ZnO was improved significantly by Cr doping. In particular, the enhanced gas-sensing mechanism was investigated by first-principles calculations upon proposed surface adsorption models. The calculated results revealed that the Cr-doped ZnO (0 0 0 1) surface enabled transfer larger electrons and adsorb more oxygen molecules than that of undoped one, thus holding the potential for further enhancement in gas response of ZnO-based sensors. [ABSTRACT FROM AUTHOR]

The selection of electrode materials and the optimization of electrode configurations are two effective approaches to achieve high-performance energy storage. As a representative ternary metal oxide, CoMoO 4 has been directly grown on the carbon cloth via a facile hydrothermal method and subsequent calcination, forming a binder-free electrode. Further measurements reveal that this electrode is composed of CoMoO 4 nanosheets assembled 3D-framworks (NAFs) and thereby shows a superb electrochemical property in KOH solution. It is worth mentioning that the specific capacitance reaches as high as 1234 F/g at the current density of 1 A/g, which exceeds most of CoMoO 4 and CoMoO 4 -based composites reported so far. Meanwhile, when the current density increases to 10 A/g, a considerable specific capacitance of 446 F/g is still obtained and can maintain nearly unchanged after 5000 cycles. [ABSTRACT FROM AUTHOR]

It is of great significance to monitor internal faults of transformer and ensure its normal and safe operation. Usually, acetylene (C 2 H 2) is considered as the characteristic gas caused by discharge failure in transformer. Using gas sensor technology to analyze dissolved gases in transformer oil is an important strategy. Recently, metal oxide semiconductor (MOS) heterojunctions with tailored microstructures have been developed to fabricate high quality gas sensors for gas detection. In this paper, hierarchical flower-like NiO/ZnO heterostructures assembled with 2D nanosheets have been synthesized by a facile hydrothermal method and calcination process. Noticeably, the introduction of different contents of NiO (3.0 at%, 5.0 at% and 10.0 at%) leads to different assembly manners of the building nanosheets into hierarchical flower-like structures, thus affecting the gas performances. Given this, a variety of microscopic characterization methods were used to observe and compare the differences in the structures and morphologies of the composites. Through the gas sensing test, it was found that the 5.0 at% NiO-modified ZnO based sensor exhibited superior sensing performances to C 2 H 2 compared with that of others. The enhanced properties may be attributed to the formation of p-n heterojunctions as well as high porosity of the nanosheets. This promising approach is versatile for the applications of high-quality gas sensors. [ABSTRACT FROM AUTHOR]

Pd-doped SnO 2 nanofibres were prepared by electrospinning and magnetron sputtering. It was found that the efficiency of gas sensing properties in these fibres depends primarily on the density of oxygen vacancies, which can be regulated by plasma treatment. We demonstrated that moderate plasma treatment can increase the oxygen vacancy as well as improve the gas sensing performance of SnO 2. However, excessive plasma treatment led to the production of other substances that deteriorated the gas sensing performance. Furthermore, the best results for hydrogen gas sensing were obtained when the nanofibres were subjected to plasma treatment for 1 min. The fabricated material demonstrated a response of more than 53 for 500 ppm hydrogen at the optimum temperature (130 °C), which is a significant improvement as compared to sensors without plasma treatment. Evidently, plasma treatment is an effective method to further enhance the sensing properties of the fabricated nanofibres. [ABSTRACT FROM AUTHOR]

In this paper, we present the synthesis of novel three-dimensional SnO 2 /MoS 2 nanocomposites via electrospinning combined with a hydrothermal method and their application to CH 4 gas detection. Morphological characterization proved that the flower-like MoS 2 structures were successfully connected to the surface of porous SnO 2 nanofibers. The CH 4 gas-sensing test results indicated that the gas-sensing properties of SnO 2 /MoS 2 nanocomposites were better than those of pure MoS 2 ; the SnO 2 /MoS 2 nanocomposites exhibited lower optimal operation temperature and higher gas response. Such excellent performance is mainly attributable to the special hierarchical structure and the existence of n–n junctions between SnO 2 and MoS 2. [ABSTRACT FROM AUTHOR]

Acetylene (C 2 H 2) gas concentration is a key parameter in transformer monitoring. In current work, the selective acetylene sensors which based on flower-like ZnO structures with NiO nanoparticles were successfully fabricated. The NiO–ZnO composites were synthesized by two-step hydrothermal method. And various of characterization analyses had been applied to the exploration of crystal structure and the p-n heterojunction. According to the systematic gas sensitivity tests, the response of NiO–ZnO (5%) to 50 ppm C 2 H 2 was 15.23 at 200 °C whereas the response of pure ZnO was 4.1 in the same condition. In addition, the response value of NiO–ZnO (5%) to 50 ppm C 2 H 2 was 3.6 times to 50 ppm H 2. Such a good gas-sensing property of NiO–ZnO composites is due to p-n heterojunction and high catalytic activity of NiO. [ABSTRACT FROM AUTHOR]