Photocatalytic Co-Reduction of CO₂ and Nitrate over Porphyrin Metal–Organic Frameworks: Dual Atomic Active Site and Nanostructure Synergy Enhances C–N Coupling for Urea Production

The photocatalytic co-reduction of NO₃⁻ and CO₂ (NitRR&CRR) offers a sustainable approach for urea synthesis and environment remediation. However, there is a lack of high-performance photocatalysts. Herein, we report a nanoflower-like bimetallic porphyrin metal–organic framework superstructure (Cu-TCPP(Co)-NF, TCPP = tetrakis(4-carboxyphenyl)porphyrin) as an efficient NitRR&CRR photocatalyst for urea production. Systematical investigations have revealed that the Cu and Co centers serve as the active sites for driving NitRR and CRR, respectively. The high pore volumes of nanoflower architecture can improve the light adsorption, promote the reactant enrichment, and intermediate generation. Consequently, the C–N coupling process over Cu-TCPP(Co)-NF is facilitated with reduced energy barriers and inhibited side reactions, resulting in an unprecedent urea yield of 2459.8 µg h⁻¹ g_cat⁻¹ in the absence of sacrificial agents. This study provides new insights into the design of advanced photocatalysts for urea synthesis.