Studies on Photocatalytic CO2 Reduction over NH2-Uio-66(Zr) and Its Derivatives: Towards a Better Understanding of Photocatalysis on Metal-Organic Frameworks

Metal-organic framework (MOF) NH2-Uio-66(Zr) exhibits photocatalytic activity for CO2 reduction in the presence of triethanolamine as sacrificial agent under visible-light irradiation. Photoinduced electron transfer from the excited 2-aminoterephthalate (ATA) to Zr oxo clusters in NH2-Uio-66(Zr) was for the first time revealed by photoluminescence studies. Generation of Zr-III and its involvement in photocatalytic CO2 reduction was confirmed by ESR analysis. Moreover, NH2-Uio-66(Zr) with mixed ATA and 2,5-diaminoterephthalate (DTA) ligands was prepared and shown to exhibit higher performance for photocatalytic CO2 reduction due to its enhanced light adsorption and increased adsorption of CO2. This study provides a better understanding of photocatalytic CO2 reduction over MOF-based photocatalysts and also demonstrates the great potential of using MOFs as highly stable, molecularly tunable, and recyclable photocatalysts in CO2 reduction.