- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
A facile synthesis of palladium encased Ag nanowires and its effect on fluorescence and catalysis
摘要： A facile polyol synthetic route was designed to prepare an ultra thin Pd nano sheath over Ag nanowires (NWs) forming metal-metal core–shell nanocomposites. Here we report the one pot synthesis of Pd assembly onto growing Ag NWs. Pd salts were reduced over varied time intervals during the growth process of the Ag NWs. The Pd salt was introduced after 20, 30- and 40-minutes to the growing Ag NWs. The product was designated as Ag@Pd 20, 30, and 40 on basis of introducing interval. The morphology and constituents of each product was observed using SEM coupled with EDX. XRD was employed to characterize composite material. UV-Visible was used to determine the SPR of each material along with the pure Ag NWs and palladium nanoparticles. Similarly, ?uorescence of each product was characterized using PL spectrophotometer, which was correlated with core and sheath. Finally, the catalytic reduction of nitrophenol into amino phenol by ultra thin sheet of Pd of each product was investigated and reaction order was ascertained.
关键词： core@shell,?uoroscence,catalytic reduction,Pd-Ag composites
更新于2025-11-19 16:46:39
-
Simultaneous two cross-sectional measurements of NH<sub>3</sub> concentration in bent pipe flow using CT-tunable diode laser absorption spectroscopy
摘要： Urea Selective Catalytic Reduction (urea SCR) system is widely used for diesel engine to reduce the emission of NOx by NH3 which is provided by a hydrolysis of urea water. Concentration distribution of NH3 in an exhaust pipe is an important factor for improvement of the SCR efficiency and prevention of NH3 slip and urea deposit. Therefore, it is necessary to measure two-dimensional (2D) concentration of NH3 in detail. The purpose of this study is to develop the real-time two cross-sectional measurements technology of NH3 concentration using the computed tomography-tunable diode laser absorption spectroscopy (CT-TDLAS). Theoretical NH3 concentration distribution which was reconstructed by CT agreed to CFD results and quadruple pipe’s results showed good resolution by 14th order reconstruction. Therefore, this method has enough resolution and accuracy for measuring the concentration distribution of NH3. And this method was employed in a bent pipe model demonstrated a urea SCR system. The experimental results of two cross-sectional 2D concentration of NH3 show differences of the concentration distribution of NH3 each cross-section and flow pattern like swirl flow. It was found that CT-TDLAS was an effective method to measure concentration distribution of NH3 and observe characteristics of flow. In addition, observing flow pattern enable to validate CFD results, and it helps to improve efficiency of after treatment system.
关键词： Urea selective catalytic reduction,NH3 concentration measurement,Exhaust aftertreatment,CT tunable diode laser absorption spectroscopy,Measurement and instrumentation
更新于2025-09-11 14:15:04
-
Preparation of hexagonal micro-sized α-Al2O3 platelets from a milled Al(OH)3 precursor with NH4F and NH4Cl additives
摘要： In the present work, an Ni5P4/Ni porous composite with a Ni foam as the skeleton was prepared through phosphorization calcination at 500 1C. Meanwhile, the catalytic activity of the as-prepared Ni5P4/Ni porous composite was explored for the treatment of a large-volume e?uent with a high concentration of 4-nitrophenol at room temperature. At last, the catalytic mechanism was discussed preliminarily. The results indicated that the Ni5P4/Ni porous composite possessed remarkable catalytic activity for the borohydride-assisted reduction of 4-nitrophenol. When the concentration of 4-nitrophenol was 1.0 (cid:2) 10(cid:3)3 mol L(cid:3)1, the catalytic reduction e?ciency of 4-nitrophenol was up to 99% within 13 min over the aforementioned sample. More interestingly, it was suitable for the treatment of a large-volume e?uent with a high concentration of 4-nitrophenol. Almost 99% of 4-nitrophenol (1.0 (cid:2) 10(cid:3)2 mol L(cid:3)1, 100 mL) could be removed within 30 min. Even when 4-nitrophenol was near saturation in water (5.0 (cid:2) 10(cid:3)2 mol L(cid:3)1), 4-nitrophenol could still be removed absolutely from water after a 165 min reaction in the presence of the Ni5P4/Ni porous composite. In the catalytic process, Ni5P4 could serve as the active sites and accelerate the formation of hydrogen atoms from BH4(cid:3). Meanwhile, the Ni skeleton could make the electron transfer faster in the catalytic system. Besides, the macroporous structure of the sample also played an important role in the catalysis process.
关键词： room temperature,large-volume effluent,4-nitrophenol,catalytic reduction,Ni5P4/Ni porous composite
更新于2025-09-11 14:15:04
-
Green Synthesis of Co <sub/>3</sub> O <sub/>4</sub> Nanorods for Highly Efficient Catalytic, Photocatalytic, and Antibacterial Activities
摘要： Cobalt oxide nanorods were successfully synthesized by a hot plate combustion method using the plant extract of Vitis vinifera. The plant extract as an alternative to toxic chemicals can be used generally as reducing and capping agents. The obtained nanorods were characterized by XRD, FT-IR, Raman, TEM, SAED, EDX, DRS, PL and VSM techniques for the structural, morphological, optical and magnetic properties. The XRD, FT-IR, Raman, EDX analysis confirmed the high purity of the sample. The TEM and SAED results showed the rod shape morphology of the sample. DRS and PL showed the band gap energy and emission at visible region. VSM showed the antiferromagnetic nature of the sample. The photocatalytic activities of the as-prepared cobalt oxide nanorods were investigated for the degradation of textile dying waste water. As per the standards of Indian pollution control board for industrial waste water let out into river bodies, the degradation reactions of waste water was found to be 250 mg/L at 150 min. Also, the same catalyst is used for the reduction of 4-nitrophenol and 4-nitroaniline using sodium borohydride as a reducing agent and it exhibits excellent reduction reaction, because of the high active surface sites. The time taken for the reduction reaction was 300 sec and 210 sec for 4-nitrophenol and 4-nitroaniline respectively. Also, the antibacterial activities towards the bacterial strains were studied and reported.
关键词： Cobalt Oxide,Antiferromagnetic,Antibacterial Studies,Catalytic Reduction,Vitis vinifera Plant Extract,Photocatalytic Degradation
更新于2025-09-04 15:30:14
-
Highly sensitive, stable g-CN decorated with AgNPs for SERS sensing of toluidine blue and catalytic reduction of crystal violet
摘要： SERS substrates with high sensitivity, SERS enhancement and stability are essential for fabrication of SERS sensors to detect dyes at low concentration. Such substrates generally have a versatile support bonded to metal nanoparticles of optimum size. Simple methodology that yields SERS substrates with reproducible results is mostly desired for sensor fabrication. In this study, silver ions were reduced with safe reducing agent NaBH4 to Ag metal nanoparticles (AgNPs) in the presence of previously prepared g-CN to obtain g-CN decorated with silver nanoparticles (AgNPs@g-CN) of average diameter 22 nm. The results of XPS and UV–Vis spectroscopy unambiguously establish signi?cant interaction between the nitrogen sites of g-CN and AgNPs. The AgNPs@g-CN yielded very high SERS enhancement for toluidine blue at very low concentration (2.5 9 10-09 M), and the SERS results are reproducible. The surface enhancement factor (EF) is one of the important criteria to evaluate and compare SERS materials, and it was equal to 9.13 9 106 toward toluidine blue. The catalytic activity of the substrate for the reduction of crystal violet (CV) to its leuco-form was tested with NABH4. The reaction was monitored by UV Vis spectroscopy. There was a rapid fall in intensity of CV. The reduction of CV mainly occurred via electron transfer from AgNPs, and the product did not interfere with the absorbance of CV. Hence, AgNPs@g-CN could be a convenient choice for fabrication of commercial SERS sensors for detection of dyes at low concentrations. It is also useful as a catalyst for the reduction of organic dyes.
关键词： g-CN,crystal violet,SERS,toluidine blue,AgNPs,catalytic reduction
更新于2025-09-04 15:30:14