Issue 26, 2020

Pushing the limits of the electrochemical window with pulse radiolysis in chloroform

Abstract

Pulse radiolysis (PR) enables the full redox window of a solvent to be accessed, as it does not require electrodes or electrolyte which limit the potentials accessible in voltammetry measurements. PR in chloroform has the additional possibility to enable reaching highly positive potentials because of its large ionization potential (IP). PR experiments demonstrated the formation of the (deuterated) chloroform radical cation CDCl3+˙, identifying it as the source of the broad absorption in the visible part of the spectrum. Results indicated that solutes with a redox potential up to +3.7 V vs. Fc/Fc+ can be oxidized by CDCl3+˙, which is far beyond what is possible with electrochemical techniques. Oxidation is not efficient because of rapid geminate recombination with chloride counterions, but also due to rapid decomposition of CDCl3+˙ which limits the yield of otherwise longer-lived free ions. The rapid, 6 ± 3 ns, decomposition, confirmed by two independent experiments, means that a solute must be present at a concentration >100 mM to capture >90% of the free holes formed. Addition of ethene removes the broad, overlapping absorptions from ubiquitous (chlorine atom, solute) complexes created by PR in halogenated solvents enabling clear observation of solute cations. The results also unravel the complex radiation chemistry of chloroform including the large reported value G(–CHCl3) = 12 molecules/100 eV for the decomposition of chloroform molecules.

Graphical abstract: Pushing the limits of the electrochemical window with pulse radiolysis in chloroform

Supplementary files

Article information

Article type
Paper
Submitted
10 Apr 2020
Accepted
05 Jun 2020
First published
12 Jun 2020

Phys. Chem. Chem. Phys., 2020,22, 14660-14670

Author version available

Pushing the limits of the electrochemical window with pulse radiolysis in chloroform

M. J. Bird, A. R. Cook, M. Zamadar, S. Asaoka and J. R. Miller, Phys. Chem. Chem. Phys., 2020, 22, 14660 DOI: 10.1039/D0CP01948H

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements