ELECTROCHEMISTRY OF LUTIDINIUM ON A PLATINUM SURFACE: INSIGHTS FOR CATALYSIS AND CARBON DIOXIDE REDUCTION

Abstract

Increasing levels of greenhouse gases in the atmosphere necessitate mitigative measures for carbon dioxide (CO\(_{2}\)) emissions. One recent but promising development is the renewables-powered electrocatalytic reduction of CO\(_{2}\) to value-added products. Although pyridinium has been previously observed to catalyze CO\(_{2}\) reduction using solar energy at high e ciency and low overpotential, the mechanism of this reaction on both semiconductor and metal surfaces is poorly understood. In this study,I investigate the dimethylpyridinium species 3,5- and 2,6-lutidinium, for both their e ectiveness at catalyzing CO\(_{2}\) reduction and their electrochemisty on the platinum electrode. Bulk electrolysis at reductive potentials, proton NMR, and headspace GC analysis reveal that both lutidinium species fail to produce CO\(_{2}\) reduction products to observable amounts. However, the observation of an unexpected extraneous anodic wave in cyclic voltammetry under CO\(_{2}\) atmosphere suggests an interaction between lutidinium and CO2 that has heretofore never been investigated. Step-sweep voltammetry reveals that the peak most likely results from the oxidation of a new product, possibly through a lutidinium-CO\(_{2}\) reaction. A mechanism involving the formation of a lutidinyl carbamate is proposed to explain these observations. The existence of such a compound could lend considerable insight to the mechanism of pyridinium-catalyzed CO\(_{2}\) reduction on a Pt surface.