Nanoplasmonic Sensing for Monitoring the Initial Stages of Atmospheric Corrosion of Cu Nanodisks and Thin Films

Abstract

Nanoplasmonic sensing as a powerful experimental technique for corrosion kinetics monitoring is demonstrated. Its versatility is illustrated by studies of initial corrosion carried out on model systems consisting of copper nanodisks and extended copper films in both dry (<0.5% relative humidity, RH) and humid (65 ± 5% RH) air. Samples with and without a protective self-assembled monolayer of octadecanethiol (ODT) were studied. Thus, we studied four different corrosion situations. Two versions of the technique were employed, direct and indirect nanoplasmonic sensing (INPS). The former used disk-shaped nanoparticles as both sample structures and sensing particles, the latter used extended films as the sample, with the nanoplasmonic sensing particles embedded under the sample. Corrosion kinetics were recorded with high sensitivity and high temporal resolution (submonolayer detection limit; temporal resolution 1-2 seconds). In dry air, six times lower oxidation rates were observed for ODT-covered Cu compared to bare Cu, demonstrating the protection efficiency of the ODT as a corrosion inhibitor. In humid air, a higher oxidation rate was measured for both bare (2.4 times higher) and ODT-covered (1.7 times higher) samples, compared to the same samples exposed to the dry air environment. Oxidation occurred first after a short induction period during which water was adsorbed. For the Cu nanodisks (direct sensing) and Cu films (indirect sensing) studied here, very similar oxidation kinetics were observed.

Oxidation of copper nanoparticles in water monitored in situ by localized surface plasmon resonance spectroscopy

“…22 The DM EXT rate is 7 Â 10 À4 s À1 , in agreement with similar immersions of Cu NP lms in water, 22 and slightly higher compared to humid air exposure (3 Â 10 À4 s À1 ). 42 In general, the transfer of electrons between the Cu NPs and the DI water will be responsible for the constant decrease of M EXT as pointed out already for the interaction of gold NPs with solvents and colloids. 43 Under UV illumination, the photogenerated electrons and holes in titania lm are an efficient source to react with the water, the NPs, and eventually impurities in the system.…”

“…0.1 nm surface oxide growth, in agreement with other Cu NP surface oxide growth and corrosion measurements. 15,17,19,42…”

“…Basically, the changes of the LSPR peak position and amplitude can be assigned to (i) a shrinking of the nanoparticle's metallic core, (ii) the formation and growth of an oxide layer (or corrosion layer in general) and (iii) the change of the refractive index of the nanoparticle's surrounding environment. 16,42 We have used bare Cu NPs on top of fused silica, with and without a TiO 2 layer, in which Cu NPs function as a plasmonic sensor. Our aim is to distinguish the TiO 2 layer photocatalytic effect on the oxidation of Cu in water under UV illumination.…”

Controlling Lipid Membrane Architecture for Tunable Nanoplasmonic Biosensing

“…The platform is formed via hole‐mask colloidal lithography and can be covered by a thin coat of a dielectric material. The dipole field from the LSPR penetrates the coating in order to monitor processes which occur on the film surface, including catalysis on platinum, corrosion on copper, and biomacromolecular adsorption on silicon oxide . Herein, we investigated how the material‐selective self‐assembly of lipid membranes could be exploited for development of sensing platforms to track membrane‐peptide interactions.…”

Apparatus for combined nanoscale gravimetric, stress, and thermal measurements

“…For example, a study of the corrosion of copper and aluminum nanoparticles was able to distinguish between two primary oxidative corrosion mechanisms. 19,20 Taken separately, neither the optical nor the QCM measurements could have distinguished between the different processes. By allowing optical access to the sample, our apparatus retains the ability to distinguish these processes.…”