Is Higher Current Necessary? Low-Current-Enhanced Electrocatalytic Ozonation through Synergistic Surface •OH Generation and Mass Transfer

This study challenges the conventional “higher current, better performance” paradigm in electrocatalytic ozonation (ECO) by demonstrating that reduced current operation simultaneously enhances pollutant removal, surface radical generation, and mass transfer through interface-dominated catalysis. Two systems using a TiO 2 nanoflower (TiO 2-NF )-modified porous anode coupled with graphite-loaded (GT-ECO) or pristine (PT-ECO) titanium mesh cathodes revealed fundamentally different reaction pathways. GT-ECO achieved complete p -CBA removal at 50 mA─4-fold lower than PT-ECO at 200 mA─through synergistic electrode functions: the TiO 2-NF anode enabled H 2 O 2 -independent O 3 activation, generating surface-localized •OH, while the GT cathode maintained elevated potentials for selective O 3 electroreduction without H 2 evolution. In situ electrochemical confocal fluorescence microscopy provided the first direct visualization of electric field-dependent surface •OH generation at the TiO 2-NF anode, confirming potential-regulated interfacial catalysis as the governing mechanism. Reduced current paradoxically enhances O 3 mass transfer of the O 3 at the porous anode through interfacial renewal, liquid film thinning, and bubble refinement. This anode-focused approach fundamentally departs from conventional cathode-driven H 2 O 2 -mediated strategies, enabling remarkable energy efficiency with operational safety and environmental robustness. These results emphasized the synergistic enhancement between surface catalysis and mass transfer and offered a new theoretical perspective on interfacial regulation in low-current ECO processes.