Confinement-enhanced valorization of contaminants in electrified hydrogenation membranes for water purification

Electrocatalytic hydrogenation offers an environmentally benign approach for contaminant valorization, but suffers from sluggish mass and electron transfer. Electrified membranes (EMs) represent an effective strategy to address these challenges, yet their structure-performance relationship remains inadequately understood. Here, we develop EMs featuring atomically dispersed Ru sites, enabling the efficient hydrogenation of nitrate, trichloroacetic acid, and phenol. A volcano-shaped relationship is observed between electrocatalytic activity and pore size. The EM with a pore size of 7 μm (EM₇) achieves 94% nitrate removal within 55 s, exhibiting over 97% selectivity towards ammonium and a 2.5 times higher kinetic constant (2.7 min^-1) than that of EM with 80 μm pores (EM₈₀). However, further reducing the pore diameter to 4 μm diminishes performance. Multiphysics simulations reveal that smaller pores enhance mass transfer but worsen current distribution uniformity. Elucidating this spatial confinement effect offers a guiding design principle of cost-effective electrodes for sustainable wastewater treatment.