4. Conclusion

(1) The cheap carbon black and graphite mixed with common PTFE and pore-forming agent are used to construct binary phase region and hierarchical pore structure at mesoscopic scale, forming an efficient gas transmission and dispersion network system, which greatly increases the electrochemical surface area of the catalyst. This simple interface engineering strategy can also be used as a reference for other reaction systems requiring gas-solid-liquid three-phase interfaces.
(2) A gas diffusion electrode with reaction layer and diffusion layer is developed. Gas enters from one side and escapes from the other. A triphase-interfacial 2e- ORR system over a carbon + PTFE catalyst enables the reactant O2 to reach the reaction interface directly from the ambient atmosphere, which simultaneously enhances the reaction rate and suppresses the competitive hydrogen evolution. Under the designed 20ml H-type reaction device and optimized conditions, the generation rate of H2O2 reaches 2.50mmol•cm-2•h-1, and the Faraday efficiency is 79%, and the cumulative H2O2 concentration reaches 11.8wt%.
(3) Based on the model of thin plate electrode, the polarization curve equation is derived and established. Simulation finds that the actual device polarization processes involve electrochemical polarization and liquid resistance ohm polarization occurred in the reaction layer, and ohmic polarization of resistance of bulk phase electrolyte. The effective reaction depth of electrode decreases rapidly with the increase of overpotential. Therefore, it is of great significance to pay more attention to the improvement of catalyst activity. The simulation also shows that with the increase of current density, the energy consumed by ohmic polarization of bulk phase electrolyte increases greatly, which is a problem to be paid attention to in engineering. The simulation and theoretical analysis of the performance of the pair of electrodes are also useful for the engineering research and improvement of other gas diffusion electrodes.
Supported by the National Natural Science Foundation of China (Grant No. 21376226).