Steering from C ₁ to C ₂ Products from the Photocatalytic CO ₂ Conversion over Correlated Single-Atom Pairs

High Resolution Image Download MS PowerPoint Slide The urgent need to mitigate accelerating CO 2 emissions has driven intense interest in photocatalytic CO 2 reduction (CO 2 RR), a process that mimics natural photosynthesis to generate carbon-neutral, value-added chemicals. While efficiency has improved, the selective production of high-value C 2+ products rather than C 1 compounds remains a critical challenge to economic viability. Single-atom catalysts offer promise for steering selectivity, yet how atomic-scale spatial distribution dictates reaction pathways remains poorly understood. Here, we demonstrate a programmed spatial distribution approach to induce synergistic cooperativity between neighboring Cu motifs within a UiO-67 matrix. By precisely modulating site distribution, we reveal a spatial threshold at which the framework transitions from isolated sites favoring C 1 products to correlated single-atom pairs (CSAPs) that facilitate C–C bond formation. Temperature-resolved electron paramagnetic resonance spectroscopy provides compelling evidence for the distribution-dependent proximity, capturing a unique magnetic feature that emerges as torsional linker motions are suppressed. This structural configuration utilizes the inherent rotational flexibility of the linkers to dynamically optimize interatomic distances, effectively stabilizing [OC–CO]* dimer intermediates and steering the reaction toward C 2 products.