The interfacial perimeter of gold nanocatalysts is popularly viewed as the active sites for a number of chemical reactions,while the geometrical structure of the interface at atomic scale is less known.Here,TiO2-nanosheets and nanospindles were adapted to accommodate Au particles(~2.2 nm),forming Au-TiO2{001}and Au-TiO2{101}interfaces.Upon calcination at 623 K in air,HAADF-STEM images evidenced that the Au particles on TiO2{101}enlarged to 3.1 nm and these on TiO2{001}remained unchanged,suggesting the stronger metal-support interaction on TiO2{001}.Au/TiO2{001}was more active for CO oxidation than Au/TiO2{101}system.
Bin ShaoWenning ZhaoShu MiaoJiahui HuangLili WangGao LiWenjie Shen
以三甲基磷氧(TMPO)和三丁基磷氧(TBPO)为探针分子,用31P魔角旋转核磁共振(31P MAS NMR)法对稀土改性Y型分子筛的酸性进行了定性和定量分析.结果表明,以TMPO为探针分子的31P MAS NMR谱分别在δ=78,70,65,62,58,55和53处存在与酸中心相关的吸收峰,其中δ=78和70处吸收峰与分子筛内部和外部酸性有关,δ=65,62,58和53处吸收峰归属于TMPO在分子筛内部Brnsted酸中心上的贡献,δ=55处吸收峰归属于TMPO在分子筛内部Lewis酸中心上的贡献.随着稀土含量的增加,中等强度Brnsted酸中心(δ=62和58)数量显著增加,而强Brnsted酸中心(δ=65)和较弱Lewis酸中心(δ=55)数量显著降低.结合分子筛骨架铝和非骨架铝对分子筛酸性的影响进一步探讨了稀土改型Y分子筛的酸性.
