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Environmental Electrometry with Luminescent Carbon Nanotubes.

ABSTRACT: We demonstrate that localized excitons in luminescent carbon nanotubes can be utilized to study electrostatic fluctuations in the nanotube environment with sensitivity down to the elementary charge. By monitoring the temporal evolution of the cryogenic photoluminescence from individual carbon nanotubes grown on silicon oxide and hexagonal boron nitride, we characterize the dynamics of charge trap defects for both dielectric supports. We find a one order of magnitude reduction in the photoluminescence spectral wandering for nanotubes on extended atomically flat terraces of hexagonal boron nitride. For nanotubes on hexagonal boron nitride with pronounced spectral fluctuations, our analysis suggests proximity to terrace ridges where charge fluctuators agglomerate to exhibit areal densities exceeding those of silicon oxide. Our results establish carbon nanotubes as sensitive probes of environmental charge fluctuations and highlight their potential for applications in electrometric nanodevices with all-optical readout.

SUBMITTER: Noe JC

PROVIDER: S-EPMC6692058 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature

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Environmental Electrometry with Luminescent Carbon Nanotubes.

Noé Jonathan C JC Nutz Manuel M Reschauer Jonathan J Morell Nicolas N Tsioutsios Ioannis I Reserbat-Plantey Antoine A Watanabe Kenji K Taniguchi Takashi T Bachtold Adrian A Högele Alexander A

Nano letters 20180625 7

We demonstrate that localized excitons in luminescent carbon nanotubes can be utilized to study electrostatic fluctuations in the nanotube environment with sensitivity down to the elementary charge. By monitoring the temporal evolution of the cryogenic photoluminescence from individual carbon nanotubes grown on silicon oxide and hexagonal boron nitride, we characterize the dynamics of charge trap defects for both dielectric supports. We find a one order of magnitude reduction in the photolumines ...[more]

PMID: 29921119

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Project description:Carbon nanotube (CNT) production is rapidly growing, and there is a need for robust analytical methods to quantify CNTs at environmentally relevant concentrations in complex organic matrices. Because physical and thermal properties vary among different types of CNTs, we studied 14 single-walled (SWCNTs) and multiwalled CNTs (MWCNTs). Our aim was to apply a classic analytical air pollution method for separating organic (OC) and elemental carbon (EC) (thermal optical transmittance/reflectance, TOT/R) to environmental and biological matrices and CNTs. The TOT/R method required significant modification for this analysis, which required a better understanding of the thermal properties of CNTs. An evaluation of the thermal properties of CNTs revealed two classes that could be differentiated using Raman spectroscopy: thermally "weak" and "strong." Using the programmed thermal analysis (PTA) method, we optimized temperature programs and instituted a set of rules for defining the separation of OC and EC to quantify a broad range of CNTs. The combined Raman/PTA method was demonstrated using two environmentally relevant matrices (cyanobacteria (CB) and urban air). Thermal evaluation of CB revealed it to be a complex matrix with interference occurring for both weak and strong CNTs, and thus a pretreatment method was necessary. Strong CNT masses of 0.51, 2.7, and 11 μg, corresponding to concentrations of 10, 54, and 220 μg CNT/g CB, yielded recoveries of 160 ± 29%, 99 ± 1.9%, and 96 ± 3.0%, respectively. Urban air was also a complex matrix and contained a significant amount (12%) of background EC that interfered greatly with weak CNTs and minimally with strong CNTs. The current detection limit at 99% confidence for urban air samples and strong CNTs is 55 ng/m(3) (0.33 μg). Overall, the PTA method presented here provides an initial approach for quantifying a wide range of CNTs, and we identify specific future research needs to eliminate potential interferences and lower detection limits.

Project description:The industrial use and widespread application of carbon-based nanomaterials have caused a rapid increase in their production over the last decades. However, toxicity of these materials is not fully known and is still being investigated for potential human and ecological health risks. Detecting carbon-based nanomaterials in the environment using current analytical methods is problematic, making environmental fate and transport modeling a practical way to estimate environmental concentrations and assess potential ecological risks. The Water Quality Analysis Simulation Program 8 (WASP8) is a dynamic, spatially resolved fate and transport model for simulating exposure concentrations in surface waters and sediments. Recently, WASP has been updated to incorporate processes for simulating the fate and transport of nanomaterials including heteroaggregation and phototransformation. This study examines the fate and transport of multiwalled carbon nanotubes (MWCNT), graphene oxide (GO) and reduced graphene oxide (rGO) in four aquatic ecosystems in the southeastern United States. Sites include a seepage lake, a coastal plains river, a piedmont river and an unstratified, wetland lake. A hypothetical 50-year release is simulated for each site-nanomaterial pair to analyze nanomaterial distribution between the water column and sediments. For all nanomaterials, 99% of the mass loaded moves though systems of high and low residence times without being heteroaggregated and deposited in the sediments. However, significant accumulation in the sediments does occur over longer periods of time. Results show that GO and rGO had the highest mass fraction in the water column of all four sites. MWCNT were found predominantly in the sediments of the piedmont river and seepage lake but were almost entirely contained in the water column of the coastal plains river and wetland lake. Simulated recovery periods following the release estimate 37+?years for lakes and 1-4?years for rivers to reduce sediment nanomaterial concentrations by 50% suggesting that carbon-based nanomaterials have the potential for long-term ecological effects.

Dataset Information

Environmental Electrometry with Luminescent Carbon Nanotubes.

Publications

Environmental Electrometry with Luminescent Carbon Nanotubes.

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