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 three‐dimensional 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 (OVs). 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, and 0.04% CO2 in Ar. 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.