State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, People's Republic of China.
ACS Nano. 2013 Jun 25;7(6):4902-10. doi: 10.1021/nn401446p. Epub 2013 May 23.
Thin porous alumina sheets have been synthesized using a lysine-assisted hydrothermal approach resulting in an extraordinary catalyst support that can stabilize Au nanoparticles at annealing temperatures up to 900 °C. Remarkably, the unique architecture of such an alumina with thin sheets (average thickness ~15 nm and length 680 nm) and rough surface is beneficial to prevent gold nanoparticles from sintering. HRTEM observations clearly showed that the epitaxial growth between Au nanoparticles and alumina support was due to strong interfacial interactions, further explaining the high sinter-stability of the obtained Au/Al2O3 catalyst. Consequently, despite calcination at 700 °C, the catalyst maintains its gold nanoparticles of size predominantly 2 ± 0.8 nm. Surprisingly, catalyst annealed at 900 °C retained the highly dispersed small gold nanoparticles. It was also observed that a few gold particles (6-25 nm) were encapsulated by an alumina layer (thickness less than 1 nm) to minimize the surface energy, revealing a surface restructuring of the gold/support interface. As a typical and size-dependent reaction, CO oxidation is used to evaluate the performance of Au/Al2O3 catalysts. The results obtained demonstrated Au/Al2O3 catalyst calcined at 700 °C exhibited excellent activity with a complete CO conversion at ∼30 °C (T100% = 30 °C), and even after calcination at 900 °C, the catalyst still achieved its T50% at 158 °C. In sharp contrast, Au catalyst prepared using conventional alumina support shows almost no activity under the same preparation and catalytic test conditions.
已经使用赖氨酸辅助的水热法合成了薄的多孔氧化铝片，得到了一种非凡的催化剂载体，该载体可以在高达 900°C 的退火温度下稳定金纳米颗粒。值得注意的是，这种氧化铝具有薄片（平均厚度约为 15nm，长度为 680nm）和粗糙表面的独特结构有利于防止金纳米颗粒烧结。高分辨透射电子显微镜（HRTEM）观察清楚地表明，金纳米颗粒与氧化铝载体之间的外延生长是由于界面相互作用强，进一步解释了所获得的 Au/Al2O3 催化剂的高烧结稳定性。因此，尽管在 700°C 下煅烧，催化剂仍保持其主要尺寸为 2±0.8nm 的金纳米颗粒。令人惊讶的是，在 900°C 下退火的催化剂保留了高度分散的小金纳米颗粒。还观察到一些金颗粒（6-25nm）被氧化铝层（厚度小于 1nm）包裹，以最小化表面能，揭示了金/载体界面的表面重构。作为一个典型的、尺寸依赖的反应，CO 氧化被用来评估 Au/Al2O3 催化剂的性能。结果表明，在 700°C 下煅烧的 Au/Al2O3 催化剂表现出优异的活性，在约 30°C（T100%=30°C）时完全转化 CO，即使在 900°C 下煅烧后，催化剂仍在 158°C 时达到 T50%。相比之下，在相同的制备和催化测试条件下，使用传统氧化铝载体制备的 Au 催化剂几乎没有活性。
