Recent breakthroughs in electrochemical studies have led to reports of CO2 reduction to formic acid, formaldehyde and methanol at low overpotentials (-0.58 V vs SCE), using Pt disk working electrodes and 10 mM aqueous solutions of pyridine (Pyr) at pH 5.3 [Cole, E. B. et al. J. Am. Chem. Soc. 2010, 132: 11539�11551]. The outstanding challenge is to establish the underlying reaction mechanism. We find evidence of a reaction mechanism for aqueous electrochemical reduction of CO2 to formic acid on Pt (111) by reaction with hydrogen atoms adsorbed on the Pt surface, via an effective proton-coupled-hydride-transfer (PCHT) reaction.  Pyridinium (PyrH+) functions as a Br�nsted acid, activating CO2 during the underlying electrophilic attack on hydrogen adsorbates and maintains a high concentration of Br�nsted acid in contact with the Pt surface that is essential to replenish the surface hydrogen consumed during CO2 reduction according to the one-electron reduction to hydrogen adsorbates and pyridine. These findings are particularly relevant for new technologies that would generate fuels with carbon neutral footprint, using aqueous solutions of organic electrocatalysts for CO2 reduction at low overpotentials

Functional role of pyridinium during aqueous electrochemical reduction of CO<sub>2</sub> on Pt(111)

247th National Meeting (2014)

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Functional role of pyridinium during aqueous electrochemical reduction of CO2 on Pt(111)

Functional role of pyridinium during aqueous electrochemical reduction of CO₂ on Pt(111)