Taymaz TABARI
,
Haman TAVAKKOLI
催化学报
doi:10.1016/S1872-2067(11)60442-7
LaFe0.9Co0.1O3(LFCO) perovskite nanoparticles were prepared using a sol-gel method. The physical and chemical properties of the catalyst were determined using X-ray diffraction (XRD), transmission electron microscopy, scanning electron microscopy, scanning tun-neling microscopy, energy dispersive X-ray spectroscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The catalytic activity of the sample was evaluated using aerobic oxidation of thiols to disulfides. The XRD results indicated that the LFCO had a good crystalline phase at 750°C. The experimental data revealed that the LFCO particles were nano-sized. LFCO nanoparticles can catalyze the oxidation of various thiols, including aromatic and aliphatic thiols. The effects of reaction parameters such as temperature, solvent, and the amount of catalyst on the oxidation of 4-chlorothiophenol were investigated. In comparison with reactions using the corresponding neat complexes, i.e., Co(NO3)2·6H2O and Fe(NO3)3·9H2O, higher yields were obtained in the oxidation reaction catalyzed by LFCO nanoparti-cles.
关键词:
perovskite-type oxide
,
nanopowder
,
oxidation of thiols
,
sol-gel method
贺金梅
,
黄玉东
,
孟令辉
,
赵建颖
,
孙德智
材料科学与工艺
为了提高多壁碳纳米管(MWNTs)的吸附性能,采用超临界水(SCW)技术改性MWNTs,研究了在超临界水中不同处理温度和处理时间对MWNTs结构和形貌的影响.分别利用傅里叶变换红外光谱(FT-IR)、X-射线光电子能谱(XPS)、拉曼光谱(Haman)和扫描电子显微镜(SEM)等测试手段分析了改性前后MWNTs结构和形貌的变化.结果表明:超临界水对MWNTs有较弱的氧化能力和较强的物理刻蚀作用,处理时间对MWNTs的影响高于温度的影响.
关键词:
碳纳米管
,
超临界水
,
结构
王兵
,
熊鹰
,
黎明
,
李凯
材料科学与工艺
为确定两种典型的反应气源对制备纳米金刚石膜的影响,分别以CH_4/Ar/H_2及CH_4/N_2混合气体作为反应源,用微波等离子体化学气相沉积(MWPCVD)法制备纳米金刚石薄膜.XRD和Haman分析表明两种气源条件下得到的膜材均为金刚石多晶膜,但用CH_4/N_2气为反应源沉积的膜材中非金刚石相成分明显更多;AFM和SEM对照分析证实所有膜层的平均晶粒尺寸及表面粗糙度均在几十纳米量级,但CH_4/N_2气源沉积的膜中容易形成异常长大的晶粒,不利于表面质量的提高.研究结果表明,以CH_4/Ar/H_2混合气体作为反应气源可制备物相组成纯度更高、表面形态更为优越的纳米金刚石膜.
关键词:
化学气相沉积
,
金刚石
,
纳米膜
,
气源
