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Nanodroplet-mediated electrodeposition is a reliable method for electrodepositing nanoparticles by confining a small amount of metal-salt precursor in water nanodroplets (radius ∼400 nm) suspended in an oil continuous phase. This technique provides a great advantage in terms of nanoparticle size, morphology, and porosity. For an electrochemical reaction to proceed in the aqueous nanodroplet, the electroneutrality condition must be maintained. Classically, [NB 4 ][ClO 4 ] or a comparable salt is added to the oil continuous phase to maintain charge balance. Unfortunately, the presence of this salt in the oil phase causes some metal salts, such as HAuCl 4 , to phase transfer, disallowing the formation of gold nanoparticles. Here, we demonstrate the partitioning of HAuCl 4 is orders of magnitude lower using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) when LiClO 4 is added to the nanodroplet phase and [NBu 4 ][ClO 4 ] is not added to the continuous phase. This simple change allows for the electrodeposition of gold nanoparticles. Scanning electron microscopy shows the morphology and size distribution of gold nanoparticles obtained at different concentrations of LiClO 4 . Transmission electron microscopy in selected diffraction mode was used and it determined the gold nanoparticles obtained are polycrystalline with miller indices of (222) and (200). This work widens the variety of nanoparticles that can be electrodeposited from nanodroplets for applications in energy storage and conversion, photoelectrochemistry, and biosensing.
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This content will become publicly available on April 1, 2026
Tuning Nanoparticle Microstructure through Nanodroplet‐Mediated Electrodeposition: Applications to PtCu Alloy Nanoparticle Synthesis and Electrocatalysis
Nanoparticles are an indispensable part of our lives. From electronic devices to drug delivery to catalysis and energy storage, nanoparticles have found various important applications. Out of the many synthetic strategies to generate nanoparticles, electrodeposition has stood out due to its cost effectiveness, low time consumption and simplicity. However, traditional electrodeposition techniques have suffered from controlling the size, shape, morphology and microstructure of nanoparticles. Here, we use a technique called nanodroplet‐mediated electrodeposition, where nanodroplets carrying the metal salt precursor collide with a negatively‐biased electrode. In this work, we use this nanodroplet‐mediated electrodeposition technique along with transmission electron microscopy, selected‐area electron diffraction and high‐angle‐annular dark‐field scanning transmission electron microscopy to show control over the microstructure of single nanoparticles. Along with that, we use X‐ray photoelectron spectroscopy to get mechanistic insights behind the alteration of microstructure observed. Having achieved a control over the microstructure, we show the application by synthesising polycrystalline alloys at room temperature and evaluating the electrocatalytic behavior of the different microstructures towards the hydrogen evolution reaction. This fundamental work of controlling microstructures of single nanoparticles and its applications in alloy synthesis and electrocatalysis opens a new avenue of tuning nanoparticles for various applications.
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- Award ID(s):
- 2327563
- PAR ID:
- 10621092
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Electroanalysis
- Volume:
- 37
- Issue:
- 4
- ISSN:
- 1040-0397
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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