Microenvironment engineering of catalytic pockets in copper paddle-wheel-based hypercrosslinked microporous polymers for highly selective CO₂ photoreduction

Precise modulation of the local microenvironment surrounding metal active centers constitutes a powerful strategy for optimizing the performance of photocatalytic CO₂ reduction. In this work, a series of hypercrosslinked microporous polymers incorporating paddle-wheel copper benzoate moieties were rationally designed and synthesized. By introducing para-substituted styrene comonomers with distinct functional groups (–NH₂, –CH₃, –CO₂H, and –CF₃), the microenvironment surrounding Cu active sites was delicately and systematically regulated. Benefiting from significantly improved photogenerated charge separation efficiency and favorable surface hydrophobicity, poly(Cu₂(VB)₄-co-VBTF)-3 exhibits a CO production rate of 21.8 µmol g⁻¹ h⁻¹ with nearly 100% CO selectivity under gas–solid conditions without any sacrificial agent, representing a 3.6-fold activity enhancement compared with the Cu₂(VB)₄ monomer. This microenvironment engineering strategy offers a new avenue for the precise design of metal active sites in porous polymeric photocatalysts and provides important insights for developing efficient solar-driven CO₂ conversion technologies.