Yuyang Li,Guanghua Liu,Jiangtao Li,Kexin Chen,Gang He,Zengchao Yang,Yemao Han,Min Zhou,Laifeng Li
Bulk In-doped Cu 2 SnSe 3 samples were prepared by a fast and one-step method of high-gravity combustion synthesis . All the synthesized samples were dense with relative densities of >98%. The influence of Indium-doping on the phase composition of the samples was investigated. SEM and EDS measurements confirm the existence of SnSe and Cu 2 Se as secondary phase in the Cu 2 Sn 1−x In x Se 3 samples. In addition, the experimental results show that there is a solubility limit of indium in the Cu 2 SnSe 3 matrix. The thermoelectric properties of the samples were measured in a temperature range from 323 K to 773 K, and the Cu 2 Sn 0.8 In 0.2 Se 3 sample achieved a maximum ZT of 0.65 at 773 K, which was comparable with the best-reported result for Cu 2 SnSe 3 materials prepared by conventional sintering approaches. With much reduced time and energy consumption, high-gravity combustion synthesis may offer a more efficient and economical way for producing thermoelectric materials .
Min Ma,Lin Peng,Jiayi Li,Yunfei Zhang,Zihan Wang,Jian Bi,Daojiang Gao,Jiangtao Wu
Despite being difficult to control and identify, extremely dilute oxygen vacancies that are generally present in metal oxides have been widely reported to play an important role in tuning the performance of gas sensors. The conventional methods of oxygen vacancy regulation, i.e., oxygen vacancy engineering, require sophisticated equipment and complex procedures while being time/energy-consuming. Beyond that, the mechanisms underlying sensing properties and oxygen vacancies have not been well understood for a long time, in particular, lack quantitative relationship. An open and important question is whether and to what extent the enhanced sensing properties can be attributed only to oxygen vacancies. In this study, a facile one-step “shake and heat” treatment that simply consists of mixing the metal oxide with carbohydrate and then heating the mixture is employed to prepare controllable oxygen-vacancy hematite . The oxygen vacancy concentration of hematite is measured by a gravimetric method. The oxygen vacancy-rich hematite shows superior sensing properties toward acetone compared to the raw materials and traditional argon annealed samples. There is a 220% increase in response when the oxygen vacancy concentration reaches 1.6% and a 74% increase when the oxygen vacancy concentration is 0.4%. The enhanced sensing properties are proven to be attributed only to the oxygen vacancies in hematite by the subsequent oxygen annealing experiment. Our study provides a simple and effective synthesis strategy to prepare high-performance oxygen vacancy-rich metal oxide sensors as well as a semiquantitative relationship between sensing performance and oxygen vacancies.
“Janus-featured” hydrogels with different structure and function for each layer can be particularly important in diverse application. However, very few studies have been conducted on multifunctional Janus-featured hydrogel, and significant challenge for simple, rapid, and efficient fabrication of such hydrogels remains. Herein, Janus-featured poly(N-hydroxyethyl acrylamide) (polyHEAA) hydrogel loaded with modified silica nanoparticle was fabricated by the supergravity method. Silica nanoparticles grafted with poly(3-(dimethyl(4-vinylbenzyl) ammonio) propyl sulfonate) (polyDVBAPS) were first prepared and then introduced into progel of polyHEAA hydrogel. During the formation of the hydrogel, a supergravity resulting from centrifugation was applied, from which silica nanoparticles moved to one side of the hydrogel, forming Janus-featured hydrogels, i.e., a pristine polyHEAA layer and a composite layer. These two layers showed different properties, where the prinstine polyHEAA layer showed excellent antifouling property by resisting the bacteria adsorption (<106 cells/cm2) for up to 5 days, and the nanoparticle-loaded hydrogel layer showed excellent bacteria-releasing properties by releasing >94% adherent bacteria upon a simple treatment with 2.0 M NaCl solution for 10 min. Based on its superb biocompatibility and low biotoxicity, we expect that our interesting strategy may provide a new assumption for the fabrication of “Janus featured” hydrogel and hopefully offer reference significance for the design of hydrogel-based wound dressing in the near future.
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