Electrosynthesis of H2O2 over aerated cathode assembled by aligned titanium hollow fibers

Electrochemical two-electron oxygen reduction is an attractive in-situ H2O2 production technology. Herein, we developed a novel cathode mode to increase H2O2 production and practicality of electrochemical technology. In this mode, aligned titanium hollow fibers (TiHFs) work as an assembled aerated cathode. O2 enters through the axial microchannel and radial nanopores of TiHF to arrive at Ti-electrolyte interphase, resulting in unrestricted O2 supply and no flooding problem that plagues gas diffusion electrodes (GDEs). Using only four fibers as assembled aerated cathode, 79.3 mM H2O2 (∼0.27 wt%) was accumulated within 1 h, which was greater than most of reported values on GDEs and met the requirement of Fenton technology in wastewater treatment (0.1 wt%). Sequentially, the performance of this TiHF aerated cathode in organic degradation was confirmed via one-electron reduction of produced H2O2 to generate •OH. A long-term stability up to 60 h could be achieved for TiHF aerated cathode, which was superior to most previously reported GDEs for H2O2 electrosynthesis (typically, < 30 h). Furthermore, the working mechanism of H2O2 production is revealed via confocal laser scanning microscopy and in situ Raman. The dynamic formation-disappearance of the three-phase interface and the accumulation of reactive intermediate (such as *OOH) were responsible for high yield and good stability.