Homogeneous bismuth dopants regulate cerium oxide structure to boost hydrogen peroxide electrosynthesis via two-electron oxygen reduction†

The electrochemical synthesis of hydrogen peroxide (H₂O₂) through the two-electron oxygen reduction reaction (2e-ORR) offers a promising alternative to the traditional anthraquinone process. However, this method often suffers from sluggish kinetics. In this study, we introduce a novel bismuth-doped cerium oxide (Bi-CeO₂) composite, featuring hollow nanospheres and triangular nanoplate structures with highly dispersed Bi dopants on the CeO₂ matrix. Notably, the morphology of Bi-CeO₂ can be dynamically tuned between spheres and plates by adjusting the amounts of Bi dopants. This innovative 1%-Bi-CeO₂ catalyst exhibits an exceptional H₂O₂ selectivity of 62.3% and significantly enhanced H₂O₂ yield, reaching 1.16 mol g_cat⁻¹ h⁻¹ at 0.1 V with a high faradaic efficiency of 56.0%. Density functional theory (DFT) calculations reveal that Bi dopants effectively lower the free energy barrier for *OOH intermediate formation, thereby accelerating H₂O₂ production. Additionally, when integrated into a dual-cathode system, 1%-Bi-CeO₂ demonstrates superior performance in removing organic dyes such as rhodamine B (RhB). This work offers a groundbreaking approach for designing high-efficiency heteroatom-doped catalysts for the 2e-ORR, paving the way for more effective electrochemical systems.