Single silver nanoparticles strip in many shots
SECCM impact transients show 10 nm Ag particles often dissolve in one spike, but larger ones leave, return, and only partly oxidize.
Source
Impact and oxidation of single silver nanoparticles at electrode surfaces: one shot <i>versus</i> multiple events
What they did
Authors landed single Ag nanoparticles of 10–100 nm on glassy-carbon and gold collectors in a scanning electrochemical cell microscope and classified current–time shapes, charges, durations, and impact frequencies.
What they found
10 nm particles mostly dissolve in a few-millisecond single event. For larger particles, 60–85% of charge sits in bundled or saw-tooth transients spanning milliseconds to seconds because particles hop in and out of the tunneling region. 60–100 nm particles often leave after incomplete stripping, so impact coulometry is a poor general sizing method.
The limits
What it doesn't show
The study is Ag on GC/Au in one electrolyte window; it does not size-calibrate every nanomaterial claimed in the impact-coulometry literature.
Key terms
- SNIE
- Single-nanoparticle impact electrochemistry: current spikes when a particle hits a collector.
- SECCM
- Scanning electrochemical cell microscopy providing low-noise, fast I–t recording.
- Impact coulometry
- Inferring particle size from the charge of one stripping spike; here often misleading.
- Saw-tooth transient
- Irregular multi-peak I–t trace from repeated partial oxidations of one NP.
- Tunneling region
- Near-surface zone where the NP can exchange electrons with the electrode.
Flashcards
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Quiz yourself
10 nm Ag NPs mostly dissolve:
Common questions
Do all Ag NPs dissolve in one shot?
Mostly only ~10 nm ones; larger particles show multi-event partial stripping.
Why are size estimates from one spike wrong?
Charge often reflects a fragment, not the whole particle.
GC vs Au?
Particles linger longer near Au, so events last about twice as long.
What fraction of charge is in bundles for large NPs?
About 60–85%.
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