Synthetic Tuning of the Catalytic Properties of Au-Fe3O4 Nanoparticles
Synthetic Tuning of the Catalytic Properties of Au-Fe3O4 Nanoparticles
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DOI：
10.1002/anie.200906130
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发表时间：
2010-01-01
影响因子：
16.6
通讯作者：
Sun, Shouheng
中科院分区：
文献类型：
--
作者：
Lee, Youngmin;Angel Garcia, Miguel;Sun, Shouheng
分散在氧化物载体上的金属纳米粒子（NPs），特别是Au NPs，通常表现出比单组分NPs高得多的催化活性。[1-6]这种催化增强归因于金属和氧化物载体界面处发生的协同效应。[1-3,5,7-11]据信，金属和氧化物载体的电子结构都被电子修饰。 跨界面转移，在界面氧化物载体上产生氧空位，成为氧吸收和活化的活性位点。[7, 10–12]最近的研究似乎表明，结结构中的小Au簇是催化的真正活性源。[5, 13]这些小Au簇比扩展的Au晶体表面具有更多的低配位Au原子，并且具有更高的能量d态， 反应性更强，更容易吸收/激活 O2 分子。这一假设得到了最近对 Au/FeOx 催化剂系统的显微镜研究的进一步支持，其中 Au 对 CO 氧化的活性的起源与直径约为 0.5 nm 并包含约 10 个 Au 原子的 Au 双层簇独特相关。 [13]尽管人们在理解催化剂/载体系统的协同效应方面做出了这些努力，并且普遍认为催化剂/载体界面边界位点对于增强催化作用很重要，但对纳米级催化剂和载体的单分散催化剂/载体的研究非常有限，[14]并且没有直接证据表明复合催化剂中存在协同效应。在此，我们证明了哑铃状Au-Fe3O4 纳米粒子确实在催化 H2O2 还原方面表现出协同效应。合成了哑铃状Au-Fe3O4 NPs，并通过Au-Fe3O4 NPs的受控蚀刻从Au-Fe3O4 NPs形成单组分Au和Fe3O4 NPs，这确保了单个Au和Fe3O4 NPs具有与Au-Fe3O4 NPs相同的结构特征。我们证明，哑铃状 Au-Fe3O4 NP 比 Au 或 Fe3O4 NP 对 H2O2 还原的催化活性更高。
Metal nanoparticles (NPs), and in particular Au NPs, dispersed on an oxide support often show a much higher catalytic activity than the single-component NPs.[1–6] Such catalytic enhancement is attributed to the synergetic effect that occurs at the interface of metal and oxide support.[1–3, 5, 7–11] It is believed that the electronic structures of both the metal and the oxide support are modified by electron transfer across the interface, giving rise to oxygen vacancies on the interfacial oxide support that become active sites for oxygen absorption and activation.[7, 10–12] Recent studies seem to indicate that small Au clusters in the junction structure are the real active source for catalysis.[5, 13] These small Au clusters have more low-coordinate Au atoms than extended Au crystal surfaces, and have higher energy d states, which are more reactive and absorb/activate O2 molecules more readily. This hypothesis is further supported by a very recent microscopy study on an Au/FeOx catalyst system, in which the origin of the Au activity on CO oxidation is associated uniquely with Au bilayer clusters that are circa 0.5 nm in diameter and contain about 10 Au atoms.[13] Despite these efforts in understanding the synergetic effect in catalyst/support systems and the general belief that catalyst/support interface boundary sites are important for the enhanced catalysis, there is very limited study on monodisperse catalyst/support with both catalyst and support in nanometer scale,[14] and there is no direct evidence that the synergetic effect is present in the composite catalyst.Herein we show that the dumbbell-like Au-Fe3O4 NPs indeed show a synergetic effect in catalyzing H2O2 reduction. Dumbbell-like Au-Fe3O4 NPs were synthesized, and singlecomponent Au and Fe3O4 NPs were formed from Au-Fe3O4 NPs by a controlled etching of Au-Fe3O4 NPs, which ensures that the individual Au and Fe3O4 NPs have the same structural features as the Au-Fe3O4 NPs. We demonstrate that the dumbbell-like Au-Fe3O4 NPs are catalytically more active than either Au or Fe3O4 NPs for H2O2 reduction.