Electrochemical Glycerol Oxidation on Rhodium Surface: Mechanistic Insights and Catalytic Activity in Alkaline Medium

Abstract

This study explores the electrochemical properties of rhodium polycrystalline electrodes applied to the glycerol oxidation reaction (GOR) in an alkaline medium. Our findings demonstrate that rhodium (Rh) surfaces exhibit catalytic activity by facilitating C–C bond cleavage at low potentials. Employing in situ Fourier-transform infrared (FTIR) spectroscopy, it was possible to identify carboxylates and carbon monoxide in bridge configuration (CO_B) as the primary intermediates in GOR. At lower potentials, glycerol oxidation predominantly yields CO_B, which oxidizes to CO₂. Carboxylate compounds, such as tartronate and oxalate, emerge as the main products, highlighting the intricate reaction mechanisms facilitated by Rh surfaces. Additionally, an oscillatory pattern in the GOR process was observed, whose frequency increases with the glycerol concentration, indicating a strong correlation between glycerol and oscillatory behavior, once CO_B already formed at a low potential is the primary cause for sustaining the oscillatory process. Therefore, the insights gained from this study enhance our understanding of GOR on Rh surfaces and contribute to the development of advanced electrocatalysts for biomass-derived fuel conversion, with potential applications in electrolyzers and fuel cells.