The zirconium–metalloporphyrin PCN-222-Zn has been synthesized and studied as catalysts for photoreduction of CO₂. Compared to the pure PCN-222, the PCN-222-Zn exhibited largely enhanced formate formation rate. Remarkably, the addition of Zn(II) ions (0.5 wt%) to the PCN-222 significantly increased the formate yield rate from 28.65 μmol/g/h to 354.14 μmol/g/h after 4 h reaction, which was highest reported value among Zr-based MOFs. The fluorescence spectroscopy indicated the better charge carrier separation efficiency for PCN-222-Zn. Also, the superior CO₂ uptake abilities of PCN-222-Zn further explained the enhanced activity. We assumed that the Zr-oxo cluster and the metalloporphyrin linker formed dual photocatalytic routes. Besides, the uncoordinated porphyrin rings in 5% PCN-222-Zn can facilitate re-bonding of the broken Zn–N bonds during the photoreduction reaction, which guaranteed the long-lasting activity. This study may provide a new strategy to design novel MOF catalysts for CO₂ reduction.

锆-金属卟啉PCN-222-Zn已被合成并用作光还原CO _2的催化剂。与纯PCN-222相比，PCN-222-Zn的甲酸酯形成速率大大提高。值得注意的是，向PCN-222中添加Zn（II）离子（0.5 wt％）可使甲酸收率从4小时反应后的28.65μmol/ g / h显着提高至354.14μmol/ g / h，这是报告值最高的基于Zr的MOF。荧光光谱表明PCN-222-Zn具有更好的电荷载流子分离效率。此外，卓越的CO ₂PCN-222-Zn的吸收能力进一步解释了增强的活性。我们假设Zr-oxo簇和金属卟啉接头形成双重光催化途径。此外，5％PCN-222-Zn中未配位的卟啉环可促进光还原反应过程中断裂的Zn-N键的重新键合，从而确保持久的活性。这项研究可能提供了设计新的MOF催化剂CO的新策略₂减少。