The Effect of Polytetrafluoroethylene Content in Porous Carbon Materials on Their Structural and Electrochemical Characteristics by the Example of Oxygen Reduction to Hydrogen Peroxide

Abstract

The results on how polytetrafluoroethylene (PTFE) affects the structural and electrochemical characteristics of porous composite materials based on furnace black СН600, acetylene black А437E, and mesostructured carbon СМК-3 are analyzed. Carbon materials differ by their preparation method, texture, wettability with respect to aqueous electrolyte, and specific surface area. The characteristics of the texture of original carbon materials and their mixtures with PTFE (5–70 wt %) are determined by the low-temperature adsorption of nitrogen. The composition materials are used as the electrode material in the working layer of gas-diffusion electrodes (GDE). The effect of PTFE on the volume and size of pores, the surface area of carbon materials, the volume of pores filled with electrolyte, the electric double layer capacitance, and the parameters of Н2О2 electrogeneration from О2 in aqueous sulfuric acid solutions at the current density of 150 mA/cm2 is described. It is shown that the effect of the PTFE concentration in composite materials on their characteristics depends on the properties of carbon materials. All carbon materials listed can be used in GDE for the reduction of О2 to Н2О2. For GDE with the optimal ratio of PTFE to the carbon material, the 5 h electrolysis produces the Н2О2 solution with the concentration of 1.9–2.4 М at 65–87% current efficiency.