Potential Modulated Attenuated Total Reflectance Spectroscopy of Prussian Blue Films on ITO

Abstract

Potential modulated attenuated total reflectance (PM‐ATR) spectroscopy has been employed to study charge transfer processes in Prussian blue (PB) films deposited on indium tin oxide (ITO) electrodes. PM‐ATR is a planar waveguide‐based spectroelectrochemical technique in which the optical response of an electroactive film is measured as a function of applied potential and modulation frequency. The multiple internal reflection geometry of PM‐ATR provides a significant sensitivity advantage over the single external reflectance geometry that has been employed in most prior electroreflectance studies. The apparent electron transfer rate of PB on ITO obtained using PM‐ATR was compared to that obtained with conventional cyclic voltammetry; the respective rates, 0.33 ± 0.15 s−1 (n = 3) and 0.71 ± 0.37 s−1 (n = 10), are in good agreement.

Axially Bound Ruthenium Phthalocyanine Monolayers on Indium Tin Oxide: Structure, Energetics, and Charge Transfer Properties

“…Measurements made using TE-and TM-polarized light allow the kinetic information to be correlated with molecular orientation, which is not possible with EIS. 4,9,45 The working principle of PM-ATR is described elsewhere, 4,9,44,45,62 and the experimental procedures used in this study are given in SI. Briefly, a DC potential with a superimposed sinusoidal potential modulation of variable frequency is applied to the ITO working electrode on which the redox-active film is immobilized.…”

“…A detailed description of PM-ATR spectroscopy can be found elsewhere. 4,44,45 Briefly, experiments were performed with an ATR flow cell having a conventional three-electrode system, using the counter and pseudoreference electrodes described above. ITO slides (total thickness = ca.…”

Electron-Transfer Rate in Potential-Modulated Redox Reactions with Electro-Active Optical Waveguides

“…Spectroelectrochemical techniques are particularly useful to mitigate those difficulties by focusing solely on the faradaic process and avoiding the strong non-faradaic electrical background. [10][11][12][13][14][15][16][17][18][19][20][21][22] Based on spectroscopic optical changes that typically accompany a redox event, it is usually possible to select the wavelength of a probing light beam to uniquely capture the optical changes associated with the faradaic process and is immune to the presence and motion of background ions in the electric double layer.…”

Characterization of Charge-Transfer Kinetics at Organic/Electrode Interfaces Using Potential-modulated Attenuated Total Reflectance (PM-ATR) Spectroscopy

“…2,4 Combining potential-modulation with the ATR geometry enables the measurement of charge-transfer kinetics of monolayer to submonolayer thin films on waveguide electrodes, with selectivity to molecular subpopulations in the film provided by appropriate choice of the applied potential and the wavelength and polarization of light, as described further below. This method has been applied to study a wide variety of electrode-supported materials, including small molecule and polymeric semiconductors, [13][14][15][16][17] proteins, 18 inorganic complexes, 19 and semiconductor nanocrystals.…”