Vacancy-confinement strategy applied in electrocatalytic flow-through membrane reactors.

Confined environments can significantly enhance catalytic performance through precise structural precision and atomic-level tunability. However, the vacancy-confinement strategy for constructing high-performance Fenton-like electrocatalytic membrane reactors (ECMRs) remains largely underexplored. Herein, we report a catalytic membrane (CoMo@BN) fabricated by encapsulating Co and Mo atoms into vacancy-engineered boron nitride (BN). This approach yields a high density of metal-nitrogen coordination (M-Nx) sites through spatial boron vacancy (Bv) confinement. These sites synergize with the electrically driven process to markedly enhance peroxymonosulfate (PMS) activation and pollutant removal. Notably, the CoMo@BN-based ECMR with high electroactive surface area and low charge transfer resistance operated in flow-through mode achieved an 8.13-fold increase in mass transfer efficiency compared with flow-by mode, yielding almost complete PMS utilization and a 1.69-fold reduction in energy consumption. This consssuration stabilizes active centers and directs the reaction toward selective non-radical pathways dominated by singlet oxygen (1O2), direct electron transfer, and high-valence metal species. Density functional theory (DFT) calculations demonstrated that the synergy between boron vacancies and confined Co/Mo atoms enhances PMS adsorption and facilitates charge transfer. This study integrates convective mass transport with active site engineering, highlighting the potential of vacancy-confinement synergy to substantially improve the Fenton-like performance of ECMRs.