Bifunctional Oxygen-Defect Bismuth Catalyst toward Concerted Production of H 2 O 2 with over 150% Cell Faradaic Efficiency in Continuously Flowing Paired-Electrosynthesis System.

The electrosynthesis of hydrogen peroxide (H 2 O 2 ) from O 2 or H 2 O via the two-electron (2e - ) oxygen reduction (2e - ORR) or water oxidation (2e - WOR) reaction provides a green and sustainable alternative to the traditional anthraquinone process. Herein, a paired-electrosynthesis tactic is reported for concerted H 2 O 2 production at a high rate by coupling the 2e - ORR and 2e - WOR, in which the bifunctional oxygen-vacancy-enriched Bi 2 O 3 nanorods (O v -Bi 2 O 3 -EO), obtained through electrochemically oxidative reconstruction of Bi-based metal-organic framework (Bi-MOF) nanorod precursor, are used as both efficient anodic and cathodic electrocatalysts, achieving concurrent H 2 O 2 production at both electrodes with high Faradaic efficiencies. Specifically, the coupled 2e - ORR//2e - WOR electrolysis system based on such distinctive oxygen-defect Bi catalyst displays excellent performance for the paired-electrosynthesis of H 2 O 2 , delivering a remarkable cell Faradaic efficiency of 154.8% and an ultrahigh H 2 O 2 production rate of 4.3 mmol h -1 cm -2 . Experiments combined with theoretical analysis reveal the crucial role of oxygen vacancies in optimizing the adsorption of intermediates associated with the selective two-electron reaction pathways, thereby improving the activity and selectivity of the 2e - reaction processes at both electrodes. This work establishes a new paradigm for developing advanced electrocatalysts and designing novel paired-electrolysis systems for scalable and sustainable H 2 O 2 electrosynthesis.