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硫酸甲酸作为一个双刃剑,用于CeO2支持的Au25(SCH2CH2Ph) 18纳米集群上的CO氧化

Zili Wu¹, De-en Jiang, Amanda K P Mann

¹Chemical Science Division, ‡Center for Nanophase Materials Sciences, and §Materials Science and Technology Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.

Journal of the American Chemical Society

|April 8, 2014

概括

黄金纳米集群上的酸最初阻碍了CO吸附,但它们的去除暴露了活性位点,增强了CeO2棒上的CO氧化催化作用. 在低温反应中,电离金矿址至关重要.

科学领域:

不同质的催化剂.
纳米材料科学科学纳米材料科学
表面化学表面化学

背景情况:

在金属氧化物上支的金纳米集群是有希望的催化剂.
酸连接物稳定金纳米集群,但可以影响它们的催化活性.
了解连接物效应对于设计高效的黄金催化剂至关重要.

研究的目的:

为了研究酸盐连接体在Au25(SR) 18纳米集群的催化性能中的作用,这些纳米集群支持在CeO2棒上.
为了阐明这些催化剂上的CO氧化机制.
为了确定参与反应的活性位点的性质.

主要方法:

催化CO氧化作为探针反应.
在现场红外 (IR) 光谱和X射线吸收光谱 (XAS).
密度函数理论 (DFT) 计算和同位素标记实验.

主要成果:

完整的Au25(SR) 18纳米集群不吸附CO;对于CO吸附和催化,需要去除连接物.
在部分去除硫酸盐后,CO吸附发生在暴露的黄金原子上,特别是在高温下.
电离金位点 (Auδ+,0 < δ ≤ 1) 被确定为低温CO氧化的主要活性位点.
反应通过一种还氧化机制进行,包括CeO2激活O2和脱硫黄金位点激活CO.
硫酸酸具有双重作用,最初阻碍了催化,但在去除后使活性位点形成.

结论:

硫酸盐连接体在Au25纳米集群的催化活性中发挥着关键的,尽管复杂的作用,用于CO氧化.
部分去除硫酸盐连接体对于暴露活跃的阴阳性黄金部位至关重要,从而提高了催化性能.
这些发现为支持的金纳米集群催化剂的结构-活性关系提供了洞察力.

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