Engineering Heteronuclear Dual‐Metal Active Sites in Ordered Macroporous Architectures for Enhanced C₂H₄ Production from CO₂ Photoreduction

Photocatalytic C₂H₄ synthesis from CO₂ and H₂O by utilizing solar energy represents a promising sustainable process, yet its efficiency remains significantly limited. Herein, we proposed a dual-engineered strategy integrating 3D ordered macroporous (3DOM) architectures with heteronuclear dual-metal active sites to synergistically promote the photocatalytic C₂H₄ production. As an example, the Cu/3DOM-In₂O₃ photocatalyst was synthesized by in situ incorporating Cu single atoms (Cu SAs) into 3DOM In₂O₃ through a template-assisted pyrolysis process. The strong interaction between Cu SAs and In₂O₃ resulted in the formation of charge-polarized Cu─In active sites along with abundant oxygen vacancies (O_Vs). 3DOM architectures serving as special nanoreactors displayed significant advantages in promoting CO₂ enrichment and confining key intermediates, thereby increasing *CO coverage. Meanwhile, the charge-polarized Cu─In active sites effectively mitigated electrostatic repulsion and promoted the formation of *CO + *CHO intermediates, resulting in a thermodynamically spontaneous C─C coupling step. Therefore, the Cu/3DOM-In₂O₃ photocatalyst exhibited robust CO₂ reduction to C₂H₄, achieving high C₂H₄ evolution rates under various CO₂ concentrations, including pure CO₂, 10% CO₂ in Ar (simulated flue gas), and 0.04% CO₂ in Ar (simulated air). This work offers a novel strategy for the construction of photocatalysts with tailored microstructures and specific active sites to promote the conversion of CO₂ and H₂O into multicarbon products.