Electrocatalytic Carbon Dioxide Activation: The Rate‐Determining Step of Pyridinium‐Catalyzed CO₂ Reduction

Abstract

The reactivity of reduced pyridinium with CO(2) was investigated as a function of catalyst concentration, temperature, and pressure at platinum electrodes. Concentration experiments show that the catalytic current measured by cyclic voltammetry increases linearly with pyridinium and CO(2) concentrations; this indicates that the rate-determining step is first order in both. The formation of a carbamate intermediate is supported by the data presented. Increased electron density at the pyridyl nitrogen upon reduction, as calculated by DFT, favors a Lewis acid/base interaction between the nitrogen and the CO(2). The rate of the known side reaction, pyridinium coupling to form hydrogen, does not vary over the temperature range investigated and had a rate constant of 2.5 M(-1) s(-1). CO(2) reduction followed Arrhenius behavior and the activation energy determined by electrochemical simulation was (69±10) kJ mol(-1).

Computational investigation of the photoinduced homolytic dissociation of water in the pyridine–water complex

“…The reduction of CO 2 to formic acid and methanol by the pyridinium radical has recently been demonstrated in electrochemical experiments, in which PyH • radicals were generated by the neutralization of pyridinium cations 42,43 .…”

Organic reactions for the electrochemical and photochemical production of chemical fuels from CO2 – The reduction chemistry of carboxylic acids and derivatives as bent CO2 surrogates

“…This chemistry has been the protagonist of a series of electrochemical and photoelectrochemical studies for the pyridine-mediated conversion of CO 2 to chemical fuels [8,52].…”

“…The CO 2 fragment is first stabilized and activated into a zwitterionic carbamate (51). This species is able to undergo reductive hydrosilylation to the corresponding aldehyde (52).…”

Hydrogen Bonded Pyridine Dimer: A Possible Intermediate in the Electrocatalytic Reduction of Carbon Dioxide to Methanol

“…We previously suggested that the electrocatalytic mechanism operating in both metal-based and semiconductor-based electrochemical cells for the reduction of CO 2 involved a mediated charge transfer process in which pyridinium is first reduced at an electrode surface via a one electron charge transfer process, followed by reaction of the electrogenerated pyridinyl species with CO 2 to form a carbamate radical adduct (Scheme 1) (Cole et al, 2010;Morris et al, 2011).…”