Zr ₄ L ₆ Cage-Based Metal Boron–Imidazolate Materials for CO ₂ Photoreduction

The structural tunability and dispersibility of cage-based catalysts make their construction via multifunctional moiety integration an effective strategy. Herein we show that enhanced catalytic performance for CO₂ photoreduction can be achieved by anchoring active metal sites and boron-imidazolate ligands on versatile (Zr₄L₆)⁸⁻ (L = embonate) cages. Three (Zr₄L₆)⁸⁻ cage-based metal boron-imidazolate structures were successfully synthesized via hierarchical self-assembly and postsynthetic ion exchange, respectively. Through cocoordination of the (Zr₄L₆)⁸⁻ cage and boron-imidazolate ligands with metal ions, (Zr₄L₆)⁸⁻ cages can be organized into various structures, including 0D PTC-390-Co, 2D layer PTC-391-Cu, and the combination of ionic pair cage PTC-373-Co. When applied to photocatalytic CO₂ reduction under visible light, PTC-373-Co exhibited the highest activity, achieving a CO production rate of 970 μmol g⁻¹ h⁻¹ with a selectivity of 90% for CO over H₂. These results suggest that cage-based catalysts represent a promising avenue for photocatalysis.