Unassisted bipolar photoelectrochemical synthesis of H2O2

Photoelectrochemical bipolar systems enable bias-free H 2 O 2 synthesis by integrating light harvesting, water oxidation and oxygen reduction. However, poor selectivity due to competing 4e - pathways, slow charge transfer, and inferior stability severely limit their practical application. Herein, we present a bias-free photoelectrochemical bipolar system for H 2 O 2 production, which integrates a Zn-TiO 2 /BVO/WO 3 photoanode for the 2e - water oxidation reaction and a Ru:CuO/Nb-CBO photocathode for the 2e - oxygen reduction reaction. The photoanode suppresses *OOH intermediates to favor H 2 O 2 formation, achieving a Faradaic efficiency (FE) of 90.2% at 0.6 V RHE . The photocathode stabilizes *OOH intermediates and delivers an FE of 91.9% under the same conditions while maintaining performance for over 50 h. Practical testing under natural sunlight with 36 cm 2 electrodes achieves an FE of 163.37% and a yield of 11.44 mmol L −1 . In situ generated H 2 O 2 achieves over 99% bacterial inactivation within 60 min. This work provides an adaptive platform for solar-driven H 2 O 2 synthesis and energy conversion.