Toward Rational Design of Oxide-Supported Single-Atom Catalysts: Atomic Dispersion of Gold on Ceria
Toward Rational Design of Oxide-Supported Single-Atom Catalysts: Atomic Dispersion of Gold on Ceria
复制标题
氧化物负载单原子催化剂的合理设计：金在二氧化铈上的原子分散
DOI：
10.1021/jacs.7b01602
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发表时间：
2017-05-03
影响因子：
15
通讯作者：
Li, Jun
中科院分区：
文献类型：
--
作者：
Liu, Jin-Cheng;Wang, Yang-Gang;Li, Jun
我们构建了一个通用的化学势热力学模型，并应用从头算电子结构和分子动力学模拟，以及动力学蒙特卡罗分析，探测氧化物载体上的金属单原子催化剂（SAC）的动力学，反应性和动力学方面。我们选择Au单原子（SAs）负载在二氧化铈作为一个典型的例子来证明我们的模型可以指导高稳定性和反应性的SACs的合理设计。结果表明，在现实条件下，各种因素，如温度，压力，颗粒大小，和还原的支持可以强烈影响的稳定性和反应性的SACs通过改变SAs和金属纳米粒子（NPs）之间的相对化学势。的Au SA在二氧化铈支持的步骤网站是相当稳定的，即使在高达700 K的温度下，并表现出约10个数量级以上的CO氧化比梯田网站的反应性。值得注意的是，在反应条件下，Au SA可以动态地在小尺寸Au NPs在氧化铈载体上的界面处产生，即使没有台阶位点，这解释了金催化中令人困惑的显著尺寸效应。我们的工作强调了一个未被认识的关键作用的Au SA在金纳米催化，并提供了一个一般的方法来设计的金属SAC的氧化物载体。
We have constructed a general thermodynamic model of chemical potentials and applied ab initio electronic structure and molecular dynamics simulations, as well as kinetic Monte Carlo analysis, to probe the dynamical, reactive, and kinetic aspects of metal single-atom catalysts (SACs) on oxide support. We choose Au single atoms (SAs) supported on ceria as a typical example to demonstrate how our model can guide the rational design of highly stable and reactive SACs. It is shown that, under realistic conditions, various factors such as temperature, pressure, particle size, and the reducibility of the support can strongly affect both the stability and the reactivity of SACs by altering the relative chemical potentials between SAs and metal nanoparticles (NPs). The Au SAs at step sites of ceria support are rather stable, even at temperatures as high as 700 K, and exhibit around 10 orders of magnitude more reactivity for CO oxidation than the terrace sites. Remarkably, under reaction conditions, Au SAs can be dynamically created at the interface of small-size Au NPs on ceria support even without step sites, which accounts for the puzzling significant size effect in gold catalysis. Our work underscores an unrecognized critical role of Au SAs in gold nanocatalysis and provides a general methodology for designing the metal SACs on oxide supports.