Trans-electrode pressure of gas-diffusion electrodes significantly influencing the electrochemical hydrogen peroxide production.

Hydrogen peroxide (HO) synthesis by electrochemical two-electron oxygen reduction has garnered increasing interest as a wide range of potential applications. Gas diffusion electrodes (GDEs) can effectively promote the HO production efficiency by overcoming the oxygen mass transfer limitations but strongly influenced by the electrowetting process along the long-term operation. In this study, the effect of trans-electrode pressure (TEP) of GDE cathode on the electrowetting process was further elucidated. We controlled the TEP values of four types of GDEs: two Ni-based GDEs and two carbon cloth GDEs prepared by hot-pressing or brushing carbon black. SBA-15 was further used to regulate the microstructure of one Ni-based GDE. It was found that an optimal range of TEP occurred for all tested GDEs in terms of the max. concentration, the yield efficiency, the energy consumption, and the stability because TEP may change the triple-phase interface and influence the anti-electrowetting effect. The porosity of hot-pressed Ni GDE can maintain the TEP window and thus enhance the production of HO, likely via creating oxygen-containing functional groups and a bimodal pore structure on the electrode, revealed with several characterization techniques including SEM, CA, XPS, Raman spectra, CV and EIS. The porous Ni GDE presented an efficient and stable production of HO for 10 cycles: yielding HO at 4393.2-4602.2 mmol m h with current efficiencies of 94.2-98.7%. The best accumulated HO concentration can reach up to 3.58 ωt% HO at 10 h. The results provide an important reference for the industrial scaleup of electro-production of HO with GDEs.