晶体孪晶
材料科学
多孔性
催化作用
格子(音乐)
结晶学
活化能
化学物理
化学工程
物理化学
化学
冶金
微观结构
复合材料
物理
生物化学
工程类
声学
作者
M. Krajčı́,Satoshi Kameoka,A.‐P. Tsai
摘要
We describe a new mechanism for creation of catalytically active sites in porous gold. Samples of porous gold prepared by de-alloying Al2Au exhibit a clear correlation between the catalytic reactivity towards CO oxidation and structural defects in the fcc lattice of Au. We have found that on the stepped {211} surfaces quite common twin boundary defects in the bulk structure of porous gold can form long close-packed rows of atoms with the coordination number CN = 6. DFT calculations confirm that on these low-coordinated Au sites dioxygen chemisorbs and CO oxidation can proceed via the Langmuir–Hinshelwood mechanism with the activation energy of 37 kJ/mol or via the CO–OO intermediate with the energy barrier of 19 kJ/mol. The existence of the twins in porous gold is stabilized by the surface energy.
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