Metal nanoparticles (NPs) with decreased sizes are promising catalysts in energy and medicine. Measuring the local reactions and simultaneously acquiring molecular insights at single small NPs, however, remain an experimental challenge. Here we report on surface-enhanced Raman spectroscopic (SERS) tracking of catalytic reactions of single 13 nm gold NPs (GNPs) in situ. We designed spatially isolated (>1.5 μm of inter-dimer space) GNP dimers, each of which consisted of two GNPs with sizes of ∼200 and ∼13 nm, respectively. This design integrates the SERS and catalytic activities into a single entity, while eliminating the crosstalk between adjacent particles, which allows us to trace the redox-derived spectral evolution at single 13 nm GNPs for the first time. We also quantified the reaction kinetics of each individual GNP and analyzed the average behavior of multiple GNPs. There is a large variability among different particles, which underscores the significance of single particle analysis.

中文翻译：

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直接 SERS 追踪单个 13 nm 金纳米粒子的化学反应†

尺寸减小的金属纳米粒子（NP）是能源和医学领域有前途的催化剂。然而，测量单个小纳米粒子的局部反应并同时获取分子见解仍然是一个实验挑战。在这里，我们报告了单 13 nm 金纳米颗粒 (GNP) 原位催化反应的表面增强拉曼光谱 (SERS)追踪。我们设计了空间隔离（>1.5 μm 的二聚体间空间）GNP 二聚体，每个二聚体由两个尺寸分别为 ∼200 和 ∼13 nm 的 GNP 组成。该设计将 SERS 和催化活性集成到一个实体中，同时消除了相邻颗粒之间的串扰，这使我们能够首次追踪单个 13 nm GNP 的氧化还原衍生光谱演化。我们还量化了每个 GNP 的反应动力学，并分析了多个 GNP 的平均行为。不同颗粒之间存在很大的变异性，这强调了单颗粒分析的重要性。