Functional -PO2-mediated asymmetric CuN3 Site Enabled Synergistic Acetylene Hydrochlorination

Symmetric metal-N4 (MN4) sites represented a common configuration in single-atom catalysts (SACs) but often limited catalytic activity due to inadequate substrate polarization and activation. Herein, we overcame this fundamental limitation by precisely engineering the microenvironment around copper single-atom using P-doping to introduce non-coordinating -PO2 group, which induced the transformation of symmetric CuN4 site into low-coordinated, asymmetric electron-rich CuN3 configuration. Crucially, the CuN3 site and proximal -PO2 group, co-located at pore defect, created an enzyme-mimicking catalytic pocket. When applied for the model reaction of acetylene hydrochlorination, these biomimetic CuN3 and -PO2 catalytic units enabled the profound synergistic effect, dramatically enhancing the adsorption, activation and dissociation of HCl to form the active Cu-Clδ-/P-O-Hδ+ intermediates. Once C2H2 approached these activated species, it became polarized due to the local micro-electric field arising from the electronegativity differences between Cu-Clδ- and P-O-Hδ+, thus lowering the barrier of rate-limiting step for C2H3Cl formation. This process endowed the P-doped Cu SAC with the dramatically enhanced acetylene hydrochlorination activity far surpassing conventional Cu-based catalysts and outstanding stability (>260 hours with only 1.12% coking). This enzyme-mimetic strategy of creating synergistic catalytic microenvironment offered a powerful paradigm for designing highly efficient SACs for challenging chemical transformations.