Highly Efficient Electrochemical Production of Hydrogen Peroxide Using the GDE Technology

Abstract

This work examines the role of oxygen supply in the improvement of the hydrogen peroxide (H2O2) electrochemical production efficiency and the generation of high H2O2concentrations in electrochemical processes operated in a discontinuous mode. To conduct this study, a highly efficient Printex L6 carbon-based gas diffusion electrode (GDE) as a cathode was employed for the electrogeneration of H2O2in a flow-by reactor and evaluated the effects of lowering the operation temperature (to increase solubility) and increasing the air supply in the system on H2O2electrogeneration. The results obtained in this study show that unlike what is expected in flow-through reactors, the efficiency in the H2O2production is not affected by the solubility of oxygen when GDE is employed in the electrochemical process (using the flow-by reactor); i.e., the efficiency of H2O2production is not significantly dependent on O2solubility, temperature, and pressure. The application of the proposed PL6C-based GDE led to the generation of accumulated H2O2of over 3 g L-1at a high current density. It should be noted, however, that the application of the electrocatalyst at lower current densities resulted in higher energy efficiency in terms of H2O2production. Precisely, a specific production of H2O2as high as 131 g kWh-1was obtained at 25 mA cm-2the energy efficiency (in terms of H2O2production) values obtained in this study based on the application of the proposed GDE in a flow-by reactor at low current densities were found to be within the range of values recorded for H2O2production techniques that employ flow-through reactors.