Localized Coexistence of Moiré and Serrated Stackings in a Copper-Melamine Framework Boosts Photocatalytic CO ₂ Conversion

Metal–organic frameworks (MOFs) have attracted significant attention for photocatalytic CO2 reduction due to their tunable pore environments, abundant active sites, and diverse stacking modes. However, the effect of different interlayer stacking, particularly when multiple stacking modes coexist within the same structure, remains underexplored. Here, we report a Copper-Melamine Framework (Cu-Mel-MOF) in which AA-rotated and AA-serrated stacking structures coexist in localized region: the 60° interlayer twist in the AA-rotated stacking induces the formation of a short-range Moiré superlattice, whereas the AA-serrated stacking exhibits staggered zigzag-like interlayer offsets. Under visible light irradiation, Cu-Mel-MOF achieves CO and H2 evolution rates of 6.27 and 3.96 mmol g–1 h–1, respectively, surpassing previously reported copper-based MOF photocatalysts. Grand Canonical Monte Carlo simulations reveal that among six stacking configurations, the serrated AA and AA-rotated stackings exhibit the highest CO2 and H2O adsorption capacities. Molecular dynamics simulations show that AA-rotated stacking reduces the CO2 activation energy (Ea = 0.20 eV), facilitating CO2 molecular transport. Density functional theory calculations further indicate that AA-rotated stacking possesses a higher CO2 adsorption energy (1.17 eV), while the serrated AA stacking exhibits a lower Gibbs free energy change in the *COOH adsorption step, enhancing overall photocatalytic performance. These findings highlight the pivotal role of stacking geometry in regulating the thermodynamics and kinetics of MOF-based photocatalysis, providing insights into molecular transport mechanisms and guiding the rational design of efficient MOF photocatalysts for CO2 conversion.