Abstract
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.
Highlights
Metal nanoparticles (NPs) such as gold NPs (GNPs) have been studied and explored in a wide range of elds from chemical synthesis and energy conversion to biochemical sensing because of their unique properties, especially their promising catalytic activities.[1,2,3,4,5] Previous studies revealed that the catalytic activity of NPs is highly dependent on their structural characteristics such as the shape and size.[6,7,8] With decreasing particle size, the NPs generally exhibit superior or new catalytic properties due to the increased surface-to-volume ratios and chemical potentials.[4]
A er removing all the amine functional groups from the indium tin oxide (ITO) surface except those binding with the small GNP (S-GNP), the slides were put in an ethanol solution consisting of 4-NTP, 2naphthalenethiol (2-NT) and HDT to functionalize the S-GNPs
The GNP dimers were formed by chemical adsorption of the 200 nm large GNPs (L-GNPs) (Fig. S1b†) with HDT
Summary
Metal nanoparticles (NPs) such as gold NPs (GNPs) have been studied and explored in a wide range of elds from chemical synthesis and energy conversion to biochemical sensing because of their unique properties, especially their promising catalytic activities.[1,2,3,4,5] Previous studies revealed that the catalytic activity of NPs is highly dependent on their structural characteristics such as the shape and size.[6,7,8] With decreasing particle size, the NPs generally exhibit superior or new catalytic properties due to the increased surface-to-volume ratios and chemical potentials.[4]. We report on surface-enhanced Raman spectroscopic (SERS) tracking of catalytic reactions of single 13 nm gold NPs (GNPs) in situ.
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