Confined Construction of Artificial Electron Transfer Pathways in Cell Wall Mesopores for Enhanced Oxygen Reduction Reaction at Microbial Cathodes

Abstract Efficient electron transfer between electrodes and the intracellular membrane respiratory chain is pivotal to microbial electrocatalytic oxygen reduction reactions (ORR). However, the insulating property of the thick peptidoglycan cell wall of Gram‐positive bacteria severely restricts extracellular electron transfer (EET) efficiency. Herein, this study leverages the mesopore confinement effect within the cell wall to propose a novel EET strategy: precise confinement of polydopamine (PDA) within the mesoporous structure of the Bacillus subtilis (ND) cell wall, thereby establishing a direct electron conduit across the cellular barrier. This strategy significantly boosted the reaction kinetics of terminal oxidases in the respiratory chain. The nanohybrid bacterium ND@Glu‐PDA achieved an ORR current density of 3.59 mA cm ⁻² and a half‐wave potential of 0.57 V. In contrast, ND@PDA with PDA polymerized solely on the cell surface exhibits only marginal ORR improvement, confirming the efficacy of the mesopore confinement approach. This work provides a new design paradigm for EET modulation in Gram‐positive bacteria and lays a theoretical foundation for construction of high‐performance microbial electrocatalytic systems.