Jump to main content
Jump to site search

Issue 3, 2016
Previous Article Next Article

Mechanistic studies of pyridinium electrochemistry: alternative chemical pathways in the presence of CO2

Author affiliations

Abstract

Protonated heterocyclic amines, such as pyridinium, have been utilized as catalysts in the electrocatalytic reduction of carbon dioxide. While these represent a new and exciting class of electrocatalysts, the details of the mechanism and faradaic processes occurring in solution are unclear. We report a series of cyclic voltammetry experiments involving Pt, Ag, Au, and Cu electrodes, under both aqueous and nonaqueous conditions, directed towards gaining an improved mechanistic understanding of pyridinium electrochemistry. Surface-enhanced Raman (SER) spectroelectrochemistry was also performed on Cu film-over-nanosphere electrodes in order to identify adsorbed species. It was found that the reduction potential of pyridinium (−0.58 V vs. SCE) and its electrochemical reversibility are unique features of platinum electrodes. In contrast, the reduction potentials on Ag, Au, and Cu electrodes are ∼400 mV more negative than Pt in both the presence and the absence of CO2. SER spectroelectrochemistry of pyridinium solutions shows no evidence for a pyridinium radical or a pyridinium ion. Increased cathodic current in the presence of CO2 is only detected at scan rates less than 10 mV s−1 in aqueous solutions. The addition of CO2 resulted in a shift in the potential for the hydrogen evolution reaction. Pyridinium electrochemistry was observed under nonaqueous conditions; however no increase in cathodic current was observed when CO2 was added to the solution. Based on this set of results it is concluded that the reduction potential of pyridinium is surface dependent, CO2 acts as a pseudo-reserve of H+, and pyridinium and CO2 create an alternative mechanism for hydrogen evolution.

Graphical abstract: Mechanistic studies of pyridinium electrochemistry: alternative chemical pathways in the presence of CO2

Back to tab navigation

Supplementary files

Publication details

The article was received on 11 Aug 2015, accepted on 20 Nov 2015 and first published on 16 Dec 2015


Article type: Paper
DOI: 10.1039/C5CP04757A
Phys. Chem. Chem. Phys., 2016,18, 1578-1586

  •   Request permissions

    Mechanistic studies of pyridinium electrochemistry: alternative chemical pathways in the presence of CO2

    A. G. Peroff, E. Weitz and R. P. Van Duyne, Phys. Chem. Chem. Phys., 2016, 18, 1578
    DOI: 10.1039/C5CP04757A

Search articles by author

Spotlight

Advertisements