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Reversing the Thermodynamics of Galvanic Replacement Reactions by Decreasing the Size of Gold Nanoparticles
- Source :
- Journal of the American Chemical Society. 142:19268-19277
- Publication Year :
- 2020
- Publisher :
- American Chemical Society (ACS), 2020.
-
Abstract
- Here, we describe the surprising reactivity between surface-attached (a) 0.9, 1.6, and 4.1 nm diameter weakly stabilized Au nanoparticles (NPs) and aqueous 1.0 × 10-4 M Ag+ solution, and (b) 1.6 and 4.1 nm diameter weakly stabilized Au NPs and aqueous 1.0 × 10-5 M PtCl42-, which are considered to be antigalvanic replacement (AGR) reactions because they are not thermodynamically favorable for bulk-sized Au under these conditions. Anodic Stripping Voltammetry (ASV) and Scanning Transmission Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (STEM-EDS) mapping provide quantitation of the extent of Ag and Pt replacement as a function of Au NP diameter. The extent of the reaction increases as the Au NP size decreases. The percentage of Ag in the AuAg alloy following AGR based on ASV is 17.8 ± 0.6% for 4.1 nm diameter Au NPs, 87.2 ± 2.9% for 1.6 nm Au NPs, and an unprecedented full 100% Ag for 0.9 nm diameter Au NPs. STEM-EDS mapping shows very close agreement with the ASV-determined compositions. In the case of PtCl42-, STEM-EDS mapping shows AuPt alloy NPs with 3.9 ± 1.3% and 41.1 ± 8.7% Pt following replacement with 4.1 and 1.6 nm diameter Au NPs, respectively, consistent with qualitative changes to the ASV. The size-dependent AGR correlates well with the negative shift in the standard potential (E0) for Au oxidation with decreasing NP size.
- Subjects :
- Microscopy, Electron, Scanning Transmission
Alloy
Metal Nanoparticles
Nanoparticle
engineering.material
Biochemistry
Catalysis
Electrolytes
Colloid and Surface Chemistry
Scanning transmission electron microscopy
Alloys
Reactivity (chemistry)
Particle Size
Electrodes
Aqueous solution
Chemistry
technology, industry, and agriculture
Spectrometry, X-Ray Emission
Electrochemical Techniques
General Chemistry
Anodic stripping voltammetry
Colloidal gold
Standard electrode potential
engineering
Thermodynamics
Gold
Oxidation-Reduction
Nuclear chemistry
Subjects
Details
- ISSN :
- 15205126 and 00027863
- Volume :
- 142
- Database :
- OpenAIRE
- Journal :
- Journal of the American Chemical Society
- Accession number :
- edsair.doi.dedup.....1713c28f68cb5849af8fc693c403c5d5