Production of hydrogen from purge gases of ammonia plants in a catalytic hydrogen-permselective membrane reactor

The present study investigates hydrogen production in a hydrogen-permselective membrane reactor from purge gases of an ammonia plant. Hydrogen which initially exists in the purge gases and hydrogen that is produced from decomposition of ammonia on nickel–Alumina catalyst bed simultaneously permeate from reaction side to shell side through a thin layer of palladium–silver membrane. A sweep gas can be used in the shell side for increasing driving force. The amount of hydrogen that can be gained annually and effect of pressure, temperature, thickness of Pd–Ag layer, configuration of flow in the membrane reactor and sweep gas flow ratio have been studied. This study shows that the countercurrent mode is better than co-current mode of operation. The rate of hydrogen permeation increases with increasing of temperature, pressure and sweep gas flow rate. This approach produces and separates large amounts of hydrogen and decreases environmental impacts owing to ammonia emission.     

Efficient generation of hydrogen from biomass without carbon monoxide at room temperature – Formaldehyde to hydrogen catalyzed by Ag nanocrystals

In this paper, we present a new route for hydrogen generation from biomass at room temperature without any carbon monoxide over nano-metal-catalysts. It has been found that the Ag nanocrystals are highly efficient and stable catalysts for the CO-free hydrogen production from formaldehyde (HCHO), a model compound of biomass, at room temperature and at atmospheric pressure. By optimizing the structure and component of catalysts, reaction parameters such as temperature, catalyst amounts, oxygen, formaldehyde concentrations, and NaOH concentrations, the hydrogen generation rate has been maintained for hours without any decay. Furthermore, the apparent activation energy of the Ag catalyzed hydrogen production reaction is determined to be 11.8 kJ mol⁻¹, which was much lower than that of the literature results (65 kJ mol⁻¹) without catalyst. Because of its high hydrogen generation rate, hydrogen generation efficiency, lower activation energy, and the low cost, we speculate that this novel Ag catalyst based hydrogen generation reaction should be a promising candidate for providing hydrogen in PEMFCs at room temperature.     

海绵状Ag2O/ZnO复合光催化剂的制备及对甲醛的可见光降解

为克服纳米ZnO晶体可见光光催化活性低的缺点,以六水合硝酸锌、六亚甲基四胺和二水合草酸为原料,采用液相共沉淀-热分解法制备了六方纤锌矿型海绵状ZnO,然后在碱性条件下复合纳米Ag₂O颗粒,得到海绵状Ag₂O/ZnO复合光催化剂,并采用XRD、FTIR、紫外-可见漫反射（UV-Vis DRS）、FESEM、TEM和BET测量仪对其进行了表征;采用可见光光源,甲醛（HCHO）液体为光催化反应模型物,研究了不同摩尔比下Ag₂O/ZnO复合光催化剂的暗吸附及光催化性能。结果表明,随着Ag₂O相对含量的增加,HCHO暗吸附效果出现先增大后减小的趋势,当Ag₂O与ZnO摩尔比为1∶5时,HCHO去除率达到43.34%;另一方面,在可见光下Ag₂O/ZnO复合光催化剂对HCHO的降解率呈先增大后减小的趋势,其中Ag₂O与ZnO的摩尔比为1∶10时取得最佳降解效果,经过90 min的可见光光照后HCHO降解率达到78%,总的HCHO去除率为85%。      

食品接触材料中纳米银迁移行为研究

目的研究纳米银在不同食品模拟液中的迁移情况。方法采用电感耦合等离子体原子发射光谱法(ICP-AES)检测了纳米银保鲜盒中纳米银的含量,比较了微波消解和干法灰化的前处理效果,并研究了不同温度情况下,纳米银食品接触材料在脂肪类(正己烷)、酸性(4%乙酸)、酒精类(65%乙醇)和水性(去离子水)食品模拟液中的迁移行为。结果食品模拟溶液、温度对纳米银的迁移有影响,其中纳米银在脂肪类模拟液中的迁移速度最快,在65%乙醇中迁移速度最慢。由Fick扩散模型,建立了PVC中塑化剂的迁移规律数学模型,得到了模型的重要参数。结论本研究成果能够对食品接触材料中纳米银的安全性评价提供技术支持。     

磷酸银-介孔炭复合光催化材料性能的研究

采用共沉淀法将介孔炭与磷酸银结合,制备出磷酸银-介孔炭复合光催化材料。利用扫描电子显微镜（SEM）、透射电子显微镜（TEM）和X射线衍射等技术手段对所制备材料进行表征,结果表明随着介孔炭负载量的增大,生成的磷酸银粒子尺寸减小。所制备材料中的磷酸银为立方体型,介孔炭的加入不会影响其晶体结构,可以制得性能稳定的复合材料。采用氮气吸-脱附测试对复合光催化材料进行光催化性能的评价,主要考察了不同介孔炭负载量对材料的光催化性能的影响。同时,通过光催化实验发现,当介孔炭负载量为10%时,所得的磷酸银-介孔炭复合光催化材料光催化效果最佳,并且所制备的复合光催化材料具有再循环使用的能力。     

银基析氧催化剂的研究进展

近年来基于阳极析氧催化的电解水制氢技术引起了广泛关注,安全、高效的阳极析氧催化剂是实现该技术的核心。银基析氧催化剂具有操作条件温和、析氧过电位低及结构易于调变的特性,是一种颇具发展前景的新型阳极析氧催化剂。本文综述了Ag基析氧催化剂的制备及其在电解水制氢方面的应用,着重介绍了Ag基析氧催化剂的两种调控改性方法,包括原位调控方法和后制备调控方法,其中原位调控方法主要有电解质溶液的匹配、电解质(浓度、酸碱度、温度)的调变和工作电极的修饰,后制备调控方法主要有金属氧化物复合、石墨烯复合和银氧化物纳米晶的调控。将原位调控和后制备调控相结合,可为制备具有较低过电势、较高催化活性的新型Ag基阳极析氧催化剂提供方法指导和为后续研究提供依据。     

Mechanical integrity of flexible InZnO/Ag/InZnO multilayer electrodes grown by continuous roll-to-roll sputtering

The mechanical integrity of a flexible ZnO-doped In₂O₃ (IZO)/Ag/IZO multilayer electrode deposited onto a flexible PET substrate using a continuous roll-to-roll (R2R) sputtering system was investigated by means of outer/inner bending, twisting and stretching tests. The R2R-sputtered flexible IZO (40 nm)/Ag (12 nm)/IZO (40 nm) electrode with a sheet resistance of 5.37 Ω/sq and an optical transmittance of 87.3% exhibited superior flexibility due to existence of a ductile Ag layer with high strain failure. It was noteworthy that the failure bending radius (5.5 mm) of the inner bending test was lower than that (6.5 mm) of the outer bending test due to complete separation of the cracks on the top IZO layer during the outer bending test. In addition, the twisting test showed that the resistance of the flexible IZO/Ag/IZO electrode began to increase at an angle of 26°. Furthermore the stretching test demonstrated that the strain failure of the IZO/Ag/IZO multilayer was 2.4%, which is higher than those of conventional flexible ITO electrodes. The mechanical integrity of the R2R-sputtered IZO/Ag/IZO multilayer indicated that hybridization of an oxide and Ag metal is a promising flexible electrode scheme for next generation flexible organic solar cells.     

Ag/SiO_2/Ag组成的三角形纳米柱的光学及传感特性

研究了一种Ag/SiO2/Ag组成的三角形纳米柱的LSPR消光光谱特性及其传感特性.时域有限差分（FDTD）法计算结果表明,三棱柱结构在中间夹层SiO2后,消光光谱峰值出现红移现象,并伴随着折射率灵敏度的增加.随着中间介质层厚度的增加,上下两层金属间表面等离子体耦合逐渐减弱,消光光谱峰值红移速度减慢.当介质层厚度为60nm时,金属层间的表面等离子体耦合消失,消光光谱与折射率灵敏度不再发生变化.对于实际制作时可能出现尖角钝化的三棱柱结构,中间介质层仍然表现出对其光学及传感特性的良好的调节作用.     

膨胀石墨表面化学镀Ag及Ni-Co-Fe合金的研究

采用化学镀技术在膨胀石墨表面包覆Ag及Ni-Co-Fe合金,用扫描电子显微镜（SEM）、X射线能谱仪（EDS）、X射线衍射仪（XRD）及振动磁强计等方法对镀层形貌、组分、结构及磁性能进行表征,结果表明,膨胀石墨表面镀层较平整光滑,厚度均匀,包覆银后的膨胀石墨没有磁性能,而包覆镍铁钴、镍铁钴/银、银/镍铁钴后的膨胀石墨磁性能明显增强,饱和磁化强度σs-Ni-Fe-Co=10.2emu/g、σs-Ni-Fe-Co/Ag=6.3emu/g、σs-Ag/Ni-Fe-Co=2.4emu/g。     

Effects of Ag interlayer on the optoelectrical properties of TiON films

A sandwich structure of TiON/Ag/TiON (TAgT) multilayer films was prepared onto glass substrates using RF and DC magnetron sputtering without intentional substrate heating. The thicknesses of each layer in the TAgT films were set at 50 nm, 5 nm and 45 nm. The optoelectrical properties of the TiON films were strongly influenced by the presence of an Ag interlayer. Although the optical transmittance of the film deteriorated when an Ag interlayer was added, the films had a low resistivity of 9.0 × 10⁻⁴ Ω cm due to increased carrier density. In addition, the TAgT films show work functions of 4.4 eV, which are suitable for organic light emitting diode (OLED) applications.The experimental results indicate that TiON film manufactured with a 5-nm thick Ag interlayer is an attractive candidate for use as a transparent electrode in large area electronic applications such as solar cells and displays.