Study of Texture Effect of Gas Diffusion Electrodes Based on A 437-E Acetylene Black on the Efficiency of Electrosynthesis of H<sub>2</sub>O<sub>2</sub> from O<sub>2</sub>
The paper studied the effect of texture characteristics gas diffusion electrodes (GDE) based on A 437-E acetylene black for electrosynthesis of H2O2 from O2 in acid solution. Texture characteristics of the initial material (A 437-E) and its mixtures with hydrophobisator (fluoroplastic-4D (F-4D) were determined by the low temperature nitrogen adsorption (LTNA) method. Rate constants for hydrogen peroxide decomposition ( K chem) over these materials in acid solution were calculated. The dependence of electrochemical activity of GDE on the quantitative content of fluoroplastic-4D in the working layer was studied and process selectivity (γ) was determined. The effect of working layer texture of GDE has a substantial impact during developing highly developed surface 3-phase contact and removal efficiency of the target product from electrode pore volume. These conditions were met in electrodes with a low content of a hydrophobisator at comparatively high hydrophilic porosity. Minor microporosity of composites of working layers ensured low losses of the target product due to its heterogeneous decomposition and contributes to efficient removal from the electrode. The findings on accumulation kinetics of hydrogen peroxide during electrosynthesis from O2 in acid solution at a current density of 150 mA/cm2 in GDE with different F-4D contents were acquired. Acid solution of 2.43 М hydrogen peroxide with a current efficiency (CE) of 76 % and process selectivity of 0.69 was obtained in GDE using 5 mass % of F-4D for 5.5 h of preparative electrosynthesis.