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

The electrosynthesis of hydrogen peroxide (HO) from O or HO 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 HO production at a high rate by coupling the 2e ORR and 2e WOR, in which the bifunctional oxygen-vacancy-enriched BiO nanorods (O-BiO-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 HO 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 HO, delivering a remarkable cell Faradaic efficiency of 154.8% and an ultrahigh HO production rate of 4.3 mmol h cm. 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 HO electrosynthesis.