Salt-templated synthesis of graphite/PTFE electrode with micron-sized honeycomb pore for efficient H2O2 electrosynthesis

Hydrogen peroxide (H 2 O 2 ) in situ production via 2-electron oxygen reduction reaction (ORR) exhibits several advantageous characteristics, including safety, convenience, environmental friendliness, and the potential to replace the traditional anthraquinone process. Nevertheless, ORR occurs at the gas–liquid-solid interface, where O 2 diffusion to the electrode and H 2 O 2 transfer from the electrode to the solution are easily limited by the pore structure of the electrode, thus reducing the efficiency of H 2 O 2 electrosynthesis. Herein, the graphite/PTFE electrodes with different pore structures were prepared using a salt template to improve the gas permeability and promote mass diffusion. A series of characterization methods, including SEM, CV, and LSV were used to investigate the effect of inorganic pore-forming agents on the electrode pore structures and their oxygen reduction activity. The pore size distribution and gas permeability of the electrode were determined by bubble point characterization. Furthermore, the impact of inorganic salt addition, current density, pH, and aeration on H 2 O 2 electrosynthesis was examined. The results demonstrate that the graphite/PTFE electrode with 0.15 g NH 4 Cl as a pore-forming agent (0.15 g-Ele) shows an obvious micron-sized honeycomb pore structure and has the highest gas permeability, contributing to the mass transfer and 2-electron ORR to produce H 2 O 2 . At a current density of 30 mA·cm −2 , pH = 3.0, and O 2 aeration rate of 400 mL·min −1 , the H 2 O 2 production of 0.15 g-Ele is found to be 425.4 mg·L -1 ·g catalyst -1 ·h −1 , with a current efficiency of 62.9 % at 60 min. The continuous and repeated use results also indicate that maintaining an abundant micron-sized honeycomb pore of the electrode is crucial for improving the H 2 O 2 production and current efficiency in electrosynthesis.