Reframing Porous Carbon as a Transport Framework for High‐Rate CO 2 Electroreduction

Porous carbons are widely used as supports for Cu‐based CO 2 reduction electrodes, yet how their pore structures regulate reactant transport within the catalyst layer remains insufficiently understood. Here, carbon blacks with distinct hierarchical textural characteristics are systematically investigated, revealing a consistent association between more developed pore architecture and higher C 2 H 4 productivity. Guided by this trend, a hierarchically integrated Cu/C catalyst is designed by forming Cu nanodomains throughout the carbon framework and compared with a benchmark prepared by physically mixing commercial Cu nanoparticles with the same carbon support. The integrated Cu/K6 catalyst achieves a C 2 H 4 partial current density of 355 mA cm – 2 with a C 2 H 4 Faradaic efficiency of 50.7% at a total current density of 700 mA cm −2 . Under these conditions, Cu/K6 exhibits a cathode potential approximately 0.3 V less negative and a 20% higher C 2 H 4 partial current density than the physically mixed benchmark. Mixed kinetic‐transport analysis indicates that the integrated architecture shifts the apparent transport‐limitation threshold to higher current densities. Multiphysics computational fluid dynamics simulations further reveal shorter effective CO 2 diffusion paths and mitigated local CO 2 depletion. These findings establish hierarchical Cu–carbon integration as an effective strategy for alleviating CO 2 transport limitations and enhancing C 2 H 4 production.