Electrochemically‐Driven Geometric Restructuring of Bismuth on Helical Carbon Nanorods Boosts H ₂ O ₂ Electrosynthesis

Understanding how catalysts restructure under operational conditions is vital for identifying active sites and designing efficient electrocatalysts for the two‐electron oxygen reduction reaction (2e − ORR), a promising route for synthesis of hydrogen peroxide (H 2 O 2 ). Here, we report a bismuth (Bi)‐based electrocatalyst whose active sites reconstructed during operation. The catalyst features in situ‐formed bismuth oxide (BiO n ) species on a unique porous helical carbon nanorod, which work together synergistically. When integrated into a solid‐electrolyte cell, the electrocatalyst shows a high H 2 O 2 production rate of 20.16 mol g −1 h −1 at 550 mA cm −2 . Notably, it exhibits good durability over 100 h at a current density of 250 mA cm −2 . Additionally, it demonstrates effective degradation of various pollutants (dyes and antibiotics) as well as exhibiting antibacterial activity. Both experiment and theoretical calculation reveal that the reconstruction of surface bismuth species is the key to the enhanced catalytic performance, as it optimizes O 2 adsorption and facilitates the subsequent protonation/reduction steps in the 2e − ORR. These findings provide new insights for precisely tuning oxygen reduction selectivity and designing highly efficient and durable electrocatalysts.