Visualisation of single atom dynamics in water gas shift reaction for hydrogen generation
Visualisation of single atom dynamics in water gas shift reaction for hydrogen generation
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DOI：
10.1039/c5cy01154j
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发表时间：
2016-04
影响因子：
5
通讯作者：
P. Gai;Kenta Yoshida;M. Ward;M. Walsh;R. T. Baker;L. V. D. Water;M. J. Watson;E. Boyes
中科院分区：
文献类型：
--
作者：
P. Gai;Kenta Yoshida;M. Ward;M. Walsh;R. T. Baker;L. V. D. Water;M. J. Watson;E. Boyes
水煤气变换反应，即CO+H2O→CO_2+H_2，是多相催化反应的基础，在燃料电池、运输燃料和合成氨生产中起着重要的作用。CeO2负载的金和相关的纳米颗粒是低温WGS反应的潜在可行催化剂。WGS催化反应是一个动态过程，发生在固体催化剂表面的原子水平上。目前对该反应的理解是从静态催化剂的研究和没有单原子敏感性的间接化学研究中推断出来的。因此，WGS反应中动态原子过程的本质仍然是不可理解的。由于催化剂的反应位置及其激活和失活的原子过程随反应环境的大小和机理而变化，因此在WGS(CO+水混合物)环境中，在原子水平上实时可视化催化剂的动态是至关重要的。具有单原子分辨率的新型环境(扫描)电子显微镜被用来在受控的WGS环境中实时地直接可视化和表征实用的金/CeO2催化剂中原子结构和过程的演变。WGS的原位观察揭示了由单原子动力学形成的只有少量金原子的团簇以及低配位表面位置的催化作用。这些新的见解对纳米颗粒在化学工艺技术中的应用具有重要意义，包括运输燃料和排放控制。
The water gas shift (WGS) reaction, CO + H2O → CO2 + H2, is the basis of heterogeneous catalysis important in the generation of clean hydrogen energy for fuel cells, transportation fuels and in ammonia manufacture. Ceria supported gold and related nanoparticles are potentially viable catalysts for the low temperature WGS reaction. The WGS catalytic reaction is a dynamic process and takes place on the solid catalyst surface at the atomic level. The current understanding of the reaction is inferred from studies of static catalysts and from indirect chemical studies without single atom sensitivity. Therefore the nature of dynamic atomic processes in the WGS reaction has remained inaccessible. Since the catalyst reaction site and atomic processes by which it activates and deactivates, change both in magnitude and mechanism with the reaction environment it is of fundamental importance to visualise the dynamic catalyst at the atomic level in WGS (CO + water mixture) environments, in real time. Novel environmental (scanning) transmission electron microscope with singe atom resolution is used herein to directly visualise and characterise, in real time, evolving atomic structures and processes in practical gold/ceria catalysts in controlled WGS environments. The in situ observations in WGS have revealed the formation of clusters of only a few gold atoms resulting from single atom dynamics and the catalytic effect of low coordination surface sites. The new insights have important implications for applications of nanoparticles in chemical process technologies including for transportation fuels and emission control.