Ferric reducing reactivity assay with theoretical kinetic modeling uncovers electron transfer schemes of metallic-nanoparticle-mediated redox in water solutions

Xiangyu Bi, Paul Westerhoff

Research output: Contribution to journalArticle

Abstract

Metallic nanoparticles (NPs) can mediate electron transfer in water solutions. We report a chemical assay named "ferric reducing ability of nanoparticles" (FRAN), which is capable of probing electron fluxes at NP-water interfaces. The assay provides time-resolved colorimetric analysis for evaluating the surface reactivity of metallic NPs in redox processes and in elucidating the electron transfer schemes. FRAN includes the reduction of ferric (FeIII) to ferrous (FeII) ions by electrons transferred from NPs at the NP-water interface. In tests of 20 nm gold (Au) and silver (Ag) NPs, the plateaued FeII concentration after adequate reaction time was linearly correlated to the NP concentration. However, distinct kinetic trends, which are mathematically described by an exponential and logarithmic function, were observed between Ag and Au NPs. We developed two theoretical models, which correspond to two interfacial electron transfer schemes, to explain the difference between the materials. For Ag NPs, the occurring redox is a one-electron transfer from Ag0 to FeIII, leading to formation of Ag+ and FeII. Despite being a heterogeneous reaction including the NP solid and aqueous solution, it involves electron transfer at the interfacial region in which the collision between FeIII and Ag0 occurs in a approximately homogeneous manner, and thus its kinetics behaves as a pseudo first-order reaction. For Au NPs, an electron flux forms when electrons stored in the NP phase are "discharged" to reduce FelII at the interface, and the NPs act as electrodes. The experiments and models for FRAN can aid in the design of NP antioxidant functionality and assessment of environmental impacts of NPs in water or other fluids.

Original languageEnglish (US)
Pages (from-to)1791-1798
Number of pages8
JournalEnvironmental Science: Nano
Volume6
Issue number6
DOIs
StatePublished - Jan 1 2019
Externally publishedYes

Fingerprint

Assays
assay
Nanoparticles
electron
kinetics
Kinetics
Electrons
Water
modeling
water
Oxidation-Reduction
nanoparticle
Colorimetric analysis
Fluxes
Antioxidants
solid solution
Silver
Gold
antioxidant
Environmental impact

ASJC Scopus subject areas

  • Materials Science (miscellaneous)
  • Environmental Science(all)

Cite this

@article{6f9f198716dd406ba887fa6f23f13bc0,
title = "Ferric reducing reactivity assay with theoretical kinetic modeling uncovers electron transfer schemes of metallic-nanoparticle-mediated redox in water solutions",
abstract = "Metallic nanoparticles (NPs) can mediate electron transfer in water solutions. We report a chemical assay named {"}ferric reducing ability of nanoparticles{"} (FRAN), which is capable of probing electron fluxes at NP-water interfaces. The assay provides time-resolved colorimetric analysis for evaluating the surface reactivity of metallic NPs in redox processes and in elucidating the electron transfer schemes. FRAN includes the reduction of ferric (FeIII) to ferrous (FeII) ions by electrons transferred from NPs at the NP-water interface. In tests of 20 nm gold (Au) and silver (Ag) NPs, the plateaued FeII concentration after adequate reaction time was linearly correlated to the NP concentration. However, distinct kinetic trends, which are mathematically described by an exponential and logarithmic function, were observed between Ag and Au NPs. We developed two theoretical models, which correspond to two interfacial electron transfer schemes, to explain the difference between the materials. For Ag NPs, the occurring redox is a one-electron transfer from Ag0 to FeIII, leading to formation of Ag+ and FeII. Despite being a heterogeneous reaction including the NP solid and aqueous solution, it involves electron transfer at the interfacial region in which the collision between FeIII and Ag0 occurs in a approximately homogeneous manner, and thus its kinetics behaves as a pseudo first-order reaction. For Au NPs, an electron flux forms when electrons stored in the NP phase are {"}discharged{"} to reduce FelII at the interface, and the NPs act as electrodes. The experiments and models for FRAN can aid in the design of NP antioxidant functionality and assessment of environmental impacts of NPs in water or other fluids.",
author = "Xiangyu Bi and Paul Westerhoff",
year = "2019",
month = "1",
day = "1",
doi = "10.1039/c9en00258h",
language = "English (US)",
volume = "6",
pages = "1791--1798",
journal = "Environmental Science: Nano",
issn = "2051-8153",
publisher = "Royal Society of Chemistry",
number = "6",

}

TY - JOUR

T1 - Ferric reducing reactivity assay with theoretical kinetic modeling uncovers electron transfer schemes of metallic-nanoparticle-mediated redox in water solutions

AU - Bi, Xiangyu

AU - Westerhoff, Paul

PY - 2019/1/1

Y1 - 2019/1/1

N2 - Metallic nanoparticles (NPs) can mediate electron transfer in water solutions. We report a chemical assay named "ferric reducing ability of nanoparticles" (FRAN), which is capable of probing electron fluxes at NP-water interfaces. The assay provides time-resolved colorimetric analysis for evaluating the surface reactivity of metallic NPs in redox processes and in elucidating the electron transfer schemes. FRAN includes the reduction of ferric (FeIII) to ferrous (FeII) ions by electrons transferred from NPs at the NP-water interface. In tests of 20 nm gold (Au) and silver (Ag) NPs, the plateaued FeII concentration after adequate reaction time was linearly correlated to the NP concentration. However, distinct kinetic trends, which are mathematically described by an exponential and logarithmic function, were observed between Ag and Au NPs. We developed two theoretical models, which correspond to two interfacial electron transfer schemes, to explain the difference between the materials. For Ag NPs, the occurring redox is a one-electron transfer from Ag0 to FeIII, leading to formation of Ag+ and FeII. Despite being a heterogeneous reaction including the NP solid and aqueous solution, it involves electron transfer at the interfacial region in which the collision between FeIII and Ag0 occurs in a approximately homogeneous manner, and thus its kinetics behaves as a pseudo first-order reaction. For Au NPs, an electron flux forms when electrons stored in the NP phase are "discharged" to reduce FelII at the interface, and the NPs act as electrodes. The experiments and models for FRAN can aid in the design of NP antioxidant functionality and assessment of environmental impacts of NPs in water or other fluids.

AB - Metallic nanoparticles (NPs) can mediate electron transfer in water solutions. We report a chemical assay named "ferric reducing ability of nanoparticles" (FRAN), which is capable of probing electron fluxes at NP-water interfaces. The assay provides time-resolved colorimetric analysis for evaluating the surface reactivity of metallic NPs in redox processes and in elucidating the electron transfer schemes. FRAN includes the reduction of ferric (FeIII) to ferrous (FeII) ions by electrons transferred from NPs at the NP-water interface. In tests of 20 nm gold (Au) and silver (Ag) NPs, the plateaued FeII concentration after adequate reaction time was linearly correlated to the NP concentration. However, distinct kinetic trends, which are mathematically described by an exponential and logarithmic function, were observed between Ag and Au NPs. We developed two theoretical models, which correspond to two interfacial electron transfer schemes, to explain the difference between the materials. For Ag NPs, the occurring redox is a one-electron transfer from Ag0 to FeIII, leading to formation of Ag+ and FeII. Despite being a heterogeneous reaction including the NP solid and aqueous solution, it involves electron transfer at the interfacial region in which the collision between FeIII and Ag0 occurs in a approximately homogeneous manner, and thus its kinetics behaves as a pseudo first-order reaction. For Au NPs, an electron flux forms when electrons stored in the NP phase are "discharged" to reduce FelII at the interface, and the NPs act as electrodes. The experiments and models for FRAN can aid in the design of NP antioxidant functionality and assessment of environmental impacts of NPs in water or other fluids.

UR - http://www.scopus.com/inward/record.url?scp=85067305744&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85067305744&partnerID=8YFLogxK

U2 - 10.1039/c9en00258h

DO - 10.1039/c9en00258h

M3 - Article

VL - 6

SP - 1791

EP - 1798

JO - Environmental Science: Nano

JF - Environmental Science: Nano

SN - 2051-8153

IS - 6

ER -