Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA.
Nat Nanotechnol. 2012 Feb 19;7(4):237-41. doi: 10.1038/nnano.2012.18.
Metal nanoparticles are used as catalysts in a variety of important chemical reactions, and can have a range of different shapes, with facets and sites that differ in catalytic reactivity. To develop better catalysts it is necessary to determine where catalysis occurs on such nanoparticles and what structures are more reactive. Surface science experiments or theory can be used to predict the reactivity of surfaces with a known structure, and the reactivity of nanocatalysts can often be rationalized from a knowledge of their well-defined surface facets. Here, we show that a knowledge of the surface facets of a gold nanorod catalyst is insufficient to predict its reactivity, and we must also consider defects on the surface of the nanorod. We use super-resolution fluorescence microscopy to quantify the catalysis of the nanorods at a temporal resolution of a single catalytic reaction and a spatial resolution of ∼40 nm. We find that within the same surface facets on the sides of a single nanorod, the reactivity is not constant and exhibits a gradient from the centre of the nanorod towards its two ends. Furthermore, the ratio of the reactivity at the ends of the nanorod to the reactivity at the sides varies significantly from nanorod to nanorod, even though they all have the same surface facets.
金属纳米粒子在各种重要的化学反应中被用作催化剂，它们可以具有不同的形状，其表面的晶面和位置在催化反应性方面存在差异。为了开发更好的催化剂，有必要确定在这些纳米粒子上何处发生催化作用以及哪些结构具有更高的反应性。表面科学实验或理论可用于预测具有已知结构的表面的反应性，并且通常可以从对其明确定义的表面晶面的了解来合理化纳米催化剂的反应性。在这里，我们表明，仅了解金纳米棒催化剂的表面晶面不足以预测其反应性，我们还必须考虑纳米棒表面的缺陷。我们使用超分辨率荧光显微镜以单个催化反应的时间分辨率和约 40nm 的空间分辨率来量化纳米棒的催化作用。我们发现，在单个纳米棒的两侧相同的表面晶面上，反应性不是恒定的，而是从纳米棒的中心向其两端呈梯度变化。此外，即使它们都具有相同的表面晶面，纳米棒两端的反应性与纳米棒侧面的反应性之比也有很大差异。
