Highly Efficient Electrochemical Production of Hydrogen Peroxide Using the GDE Technology.

This work examines the role of oxygen supply in the improvement of the hydrogen peroxide (H 2 O 2 ) electrochemical production efficiency and the generation of high H 2 O 2 concentrations 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 H 2 O 2 in 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 H 2 O 2 electrogeneration. The results obtained in this study show that unlike what is expected in flow-through reactors, the efficiency in the H 2 O 2 production 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 H 2 O 2 production is not significantly dependent on O 2 solubility, temperature, and pressure. The application of the proposed PL6C-based GDE led to the generation of accumulated H 2 O 2 of over 3 g L -1 at 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 H 2 O 2 production. Precisely, a specific production of H 2 O 2 as high as 131 g kWh -1 was obtained at 25 mA cm -2 ; the energy efficiency (in terms of H 2 O 2 production) 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 H 2 O 2 production techniques that employ flow-through reactors.