Influence of the local pH on the electrooxidation of glycerol on Palladium–Rhodium electrodeposits

Abstract

Here we investigate the electrooxidation of glycerol on Palladium–Rhodium electrodeposits (atomic composition 78:22) in alkaline media. We follow the voltammetric response of the electrodeposit in the presence of Glycerol by using FTIR in situ. Results show that CO32- is the main product of glycerol electrooxidation. When low concentrations of alkaline electrolyte are used, the spectroscopic results do not emulate regular electrochemical experiments, because the consumption of OH− inside the thin layer forces the reaction to proceed through a pathway that involves the production of CO2, instead of CO32-. When 1.0moldm−3 KOH is used as electrolyte, large amounts of carbonate are produced in regions of potential which coincide with the rising of high-level currents during glycerol electrooxidation. The results attest that Palladium–Rhodium surfaces present a suitable catalytic activity towards glycerol electrooxidation and suggest that the presence of Rhodium helps to increase the low ability of Palladium to cleave C–C bonds in the strongly alkaline media.