Strong Metal-Support Interactions between Gold Nanoparticles and ZnO Nanorods in CO Oxidation
Strong Metal-Support Interactions between Gold Nanoparticles and ZnO Nanorods in CO Oxidation
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DOI：
10.1021/ja3033235
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发表时间：
2012-06-20
影响因子：
15
通讯作者：
Lin, Tien-Sung
中科院分区：
文献类型：
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作者：
Liu, Xiaoyan;Liu, Ming-Han;Lin, Tien-Sung
负载金纳米颗粒的催化性能主要取决于载体的性质。在这里，我们报告了基于结构和光谱表征结果的金纳米颗粒和ZnO纳米棒之间强金属支持相互作用（SMSI）的第一个证据。催化剂表现出氧化锌对金纳米粒子的包封和金与载体之间的电子转移。利用透射电子显微镜（TEM）、x射线光电子能谱（XPS）、x射线吸收光谱（XAS）、电子顺磁共振（EPR）和红外光谱（FTIR）对吸附的CO进行了详细的表征，并通过探测CO在Au/ZnO纳米棒上的氧化效率进一步研究了SMSI效应的意义。经典的还原性SMSI是TiO2负载的VIII族金属在H-2中高温还原后电子从载体转移到金属，而Au/ zno -纳米棒体系中的氧化性SMSI则是氧诱导的埋藏和电子从金转移到载体。在CO氧化过程中，我们发现SMSI的氧化态与带正电的金纳米粒子有关，并对其包封前后的催化活性有很强的影响。氧化SMSI可以通过氢处理来逆转，以诱导AuZn合金的形成、脱包和电子从载体转移到Au。我们对Au/ZnO纳米棒中SMSI效应的发现，为金与载体之间的相互作用提供了新的认识，并为控制金与载体之间的相互作用以及催化活性提供了新的途径。
The catalytic performances of supported gold nanoparticles depend critically on the nature of support. Here, we report the first evidence of strong metal-support interactions (SMSI) between gold nanoparticles and ZnO nanorods based on results of structural and spectroscopic characterization. The catalyst shows encapsulation of gold nanoparticles by ZnO and the electron transfer between gold and the support. Detailed characterizations of the interaction between Au nanoparticles and ZnO were done with transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), electron paramagnetic resonance (EPR), and FTIR study of adsorbed CO. The significance of the SMSI effect is further investigated by probing the efficiency of CO oxidation over the Au/ZnO-nanorod. In contrast to the classical reductive SMSI in the TiO2 supported group VIII metals which appears after high temperature reduction in H-2 with electron transfer from the support to metals, the oxidative SMSI in Au/ZnO-nanorod system gives oxygen-induced burial and electron transfer from gold to support. In CO oxidation, we found that the oxidative SMSI state is associated with positively charged gold nanoparticles with strong effect on its catalytic activity before and after encapsulation. The oxidative SMSI can be reversed by hydrogen treatment to induce AuZn alloy formation, de-encapsulation, and electron transfer from support to Au. Our discovery of the SMSI effects in Au/ZnO nanorods gives new understandings of the interaction between gold and support and provides new way to control the interaction between gold and the support as well as catalytic activity.