Silver-mediated fluorination of potassium aryltrifluoroborates with Selectfluor®

A simple and practical procedure for the silver-mediated fluorination of aryl- and heteroaryltrifluoroborates with electrophilic fluorine from Selectfluor^® and LiOH·H₂O is presented. The reaction procedure is simple and easy to set up, the process produces fluorinated arenes and heteroarenes in good to excellent yields and a wide range of electronically and structurally diverse substrates are tolerated.     

Oxirane synthesis from diazocarbonyl compounds via NHC-Ag catalysis

A new method was developed to synthesize oxirane products from the reaction of diazocarbonyl substrates with aryl aldehydes by using Ag(I) N-heterocyclic carbene complex as the catalyst. A combination of N-heterocyclic carbene silver complex (IPrAgCl) with another silver salt (AgOTf) generated the catalytic active IPr-Ag⁺ intermediate, which then catalyzed the epoxidation reaction.     

Ag/Ag3PO4/g-C3N4三元复合光催化剂的制备及其可见光驱动下的光催化活性增强

报道了一种新型Ag/Ag₃PO₄/g-C₃N₄三元复合光催化剂的制备及其半导体界面处的快速载流子分离所引起的光催化活性的显著增强效应。通过X射线衍射,扫描电子显微镜,紫外-可见吸收光谱以及光致发光光谱等就其晶体结构、形貌、组分、光学吸收以及载流子的快速分离行为进行了表征与分析。以罗丹明B作为模型化合物分子,研究发现,所制备的Ag/Ag₃PO₄/g-C₃N₄三元复合光催化剂在可见光照射下表现出比Ag₃PO₄以及Ag₃PO₄/g-C₃N₄二元催化剂更为优异的光催化活性。研究认为,Ag₃PO₄表面尺寸约为40 nm的Ag纳米粒子在可见光下受激所产生的等离子表面共振效应以及Ag₃PO₄与g-C₃N₄界面处所形成的类似异质结结构对所制备的Ag/Ag₃PO₄/g-C₃N₄三元复合光催化剂光催化活性的显著增强起到重要作用。     

Ag/SBA-15低温气相选择性催化氧化苯甲醇合成苯甲醛

以SBA-15为载体,采用浸渍法制备了不同Ag含量的Ag/SBA-15,通过N₂吸附-脱附、X射线衍射、扫描电子显微镜、高分辨透射电子显微镜、X射线光电子能谱和电感耦合等离子体质谱对催化剂进行了表征。将Ag/SBA-15用于苯甲醇气相选择性催化氧化合成苯甲醛,研究了反应条件对转化率和选择性的影响。结果表明,Ag/SBA-15具有均一的一维孔道结构、较厚的孔壁（3-5 nm）及较大的比表面积（411-541 m²/g）,其规整纳米空间的限域作用使一定负载量的Ag以纳米尺寸均匀分散于介孔SBA-15孔道内,增加了活性组分的比表面积。亲核性氧物种从Ag到SBA-15表面的氧溢流,提高了低温下Ag/SBA-15对苯甲醇气相选择性氧化合成苯甲醛的催化性能。5.3% Ag/SBA-15中的Ag粒径为5-6 nm,且均匀分散于载体孔道中,反应温度为220℃时,苯甲醇转化率为87%,苯甲醛选择性为95%;240℃时,苯甲醇转化率和苯甲醛选择性分别高达94%和97%;并在240-300℃范围内,其催化活性和选择性保持不变,表现出了良好的温度耐受能力。催化剂经活化再生可以连续使用40 h,选择性基本保持不变。     

X射线吸收谱研究碳纳米管内Rh-Mn纳米粒子结构的变化

利用X射线吸收谱技术研究了负载于多壁碳纳米管内的Rh-Mn纳米粒子在不同气氛和温度下的结构. 结果表明,Rh-Mn粒子在空气中是由氧化铑团簇和混合锰氧化物组成. 经过氢气在300 ℃下还原后,混合锰氧化物种转化成MnO. 而氧化铑团簇在He气氛下当温度达到250 ℃时就会发生分解而形成金属铑团簇. 对形成的铑团簇用H₂或CO进行热处理,发现其分散性随温度升高而提高; 同时,X射线吸收谱实验没有观察到Mn和Rh之间存在显著的相互作用,助剂Mn的主要作用是提高了Rh的分散性.     

High yield preparation of silver nanowires by CuCl2-mediated polyol method and application in semitransparent conduction electrode

High yield preparation of silver nanowires (AgNWs) was prepared by polyol method. In this developed polyol process, uniform AgNWs have been successfully synthesized at higher yield by introducing CuCl₂·2H2O, when ethylene glycol is used as the solvent and reductant while poly vinyl pyrrolidone (PVP) is used as the capper agent. Then Ag thin films were made by screen printing using silver nanowires and nanoparticles as semitransparent conduction electrodes. The test results indicated that the electrical resistivity could be as low as 0.091 Ω/□, when the transparence rate can reach 45–46%, which shows great promise in the improvement of conductive antireflection coating.     

The potential use of nanosilver-decorated titanium dioxide nanofibers for toxin decomposition with antimicrobial and self-cleaning properties

While chemical and biological attacks pose risk to human health, clean air is of scientific, environmental and physiological concerns. In the present contribution, the potential use of nanosilver-decorated titanium dioxide (TiO₂) nanofibers for toxin decomposition with antimicrobial activity and self-cleaning properties was investigated. Titanium dioxide nanofibers were prepared through sol-gel reaction followed by an electrospinning process. Following the Japan Industrial Standard (JIS) protocol, decompositions of nitrogen oxide (NOx) and volatile organic compound (VOC) by the TiO₂ nanofibers suggested that these materials were capable of air treatment. To further enhance their anti-microbial activity, silver nanoparticles were decorated onto the TiO₂ nanofibers’ surfaces via photoreduction of silver ion in the presence of the nanofibers suspension. Furthermore, tests of photocatalytic activity of the samples were performed by photodegrading methylene blue in water. The nanofibrous membranes prepared from these nanofibers showed superhydrophilicity under UV. Finally, the possibility of using these hybrid nanofibers in environmental and hygienic nanofiltration was proposed, where the self-cleaning characteristics was expected to be valuable in maintenance processes.     

AgSbSe2 and AgSb(S,Se)2 thin films for photovoltaic applications

Silver antimony selenide (AgSbSe₂) thin films were prepared by heating sequentially deposited multilayers of antimony sulphide (Sb₂S₃), silver selenide (Ag₂Se), selenium (Se) and silver (Ag). Sb₂S₃ thin film was prepared from a chemical bath containing SbCl₃ and Na₂S₂O₃, Ag₂Se from a solution containing AgNO₃ and Na₂SeSO₃ and Se thin films from an acidified solution of Na₂SeSO₃, at room temperature on glass substrates. Ag thin film was deposited by thermal evaporation. The annealing temperature was 350 °C in vacuum (10⁻³ Torr) for 1 h. X-ray diffraction analysis showed that the thin films formed were polycrystalline AgSbSe₂ or AgSb(S,Se)₂ depending on selenium content in the precursor films. Morphology and elemental analysis of these films were done using scanning electron microscopy and energy dispersive X-ray spectroscopy. Optical band gap was evaluated from the UV-visible absorption spectra of these films. Electrical characterizations were done using Hall effect and photocurrent measurements. A photovoltaic structure: glass/ITO/CdS/AgSbSe₂/Al was formed, in which CdS was deposited by chemical bath deposition. J-V characteristics of this structure showed V_oc = 435 mV and J_sc = 0.08 mA/cm² under illumination using a tungsten halogen lamp. Preparation of a photovoltaic structure using AgSbSe₂ as an absorber material by a non-toxic selenization process is achieved.     

Lateral and vertical manipulations of single atoms on the Ag(1 1 1) surface with the copper single-atom and trimer-apex tips

We study the lateral and vertical manipulations of single Ag and Cu atoms on the Ag(1 1 1) surface with the Cu single-atom and trimer-apex tips using molecular statics simulations. The reliability of the lateral manipulation with the Cu single-atom tip is investigated, and compared with that for the Ag tips. We find that overall the manipulation reliability (MR) increases with the decreasing tip height, and in a wide tip-height range the MR is better than those for both the Ag single-atom and trimer-apex tips. This is due to the stronger attractive force of the Cu tip and its better stability against the interactions with the Ag surface. With the Cu trimer-apex tip, the single Ag and Cu adatoms can be picked up from the flat Ag(1 1 1) surface, and moreover a reversible vertical manipulation of single Ag atoms on the stepped Ag(1 1 1) surface is possible, suggesting a method to modify two-dimensional Ag nanostructures on the Ag(1 1 1) surface with the Cu trimer-apex tip.