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Abstract Single entity electrochemistry experiments are typically motivated by the need to reveal how heterogeneity affects performance within inherently diverse nanoparticle populations. Here we show that a commonly used supporting electrode, tin‐doped indium oxide (ITO), can also play a significant role in creating heterogeneity in nanoparticle electrochemical responses. To investigate the impact of the substrate, we optically monitored the electrodissolution kinetics of gold nanoparticles on ITO thin films with similar resistivity from two different suppliers. The ITO from the two suppliers showed marked differences in the gold electrodissolution kinetics, with ITO from one of the suppliers even producing poor sample‐to‐sample reproducibility across substrates within the same lot number. The role of nanoparticle size and surface effects were accounted for in our analysis to validate that the observed heterogeneity is dominated by the ITO electrodes. The results show that the role of the supporting electrode cannot be ignored when performing single entity structure‐function studies.
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Nonequilibrum phase transition in the light-actuated self-assembly of nanoparticles: effects of surfaces and stochastic forces
When we illuminate gold nanofluids over indium-tin-oxide (ITO)-coated substrates, nanoparticle chains selfassemble via optical binding forces. We speculate that charge transfer between gold and ITO pins nanoparticles to the substrate and reduces the lateral Brownian motion as they attach to the substrate. We correspondingly model the self assembly with additional stochastic or random forces. Simulations show a nonequilibrium phase transition: when the stochastic force is small, nanoparticle chains align perpendicular to the light polarization and nanoparticles settle at shallow but stable nodes; when the stochastic force is large, however, the nanoparticle chains align parallel to the light polarization and nanoparticles settle at saddlepoints where the optical binding force is largely zero. Since the presence and strength of Brownian forces influence which state is formed, we reconsider the role that surfaces have—not only in relation to charge transfer but also heat transfer.
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- Award ID(s):
- 1921034
- PAR ID:
- 10166399
- Date Published:
- Journal Name:
- Optical Trapping and Optical Micromanipulation
- Volume:
- 11083
- Issue:
- XVI
- Page Range / eLocation ID:
- 1108325
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1117/12.2528987
