Bimetallic metal-organic frameworks for efficient visible-light-driven photocatalytic CO2 reduction and H2 generation

A series of robust octahedral bimetallic metal-organic frameworks, NH2-UiO-66(Zr/M), denoted as Zr/M-ATA, (where M is Fe, Co, or Cu) were prepared by solvothermal de novo reaction of 2-aminoterephthalic acid (denoted as H2ATA) and mixed metal salts using benzoic acid as a modulator. Photocatalytic studies revealed that Zr/Fe-ATA, Zr/Cu-ATA and Zr/Co-ATA containing double metals outperformed that of the monometallic Zr-ATA. Zr/Cu-ATA displayed excellent performance for visible-light-driven CO2 reduction with a formate forma-tion rate of 122 mu mol h-1 mmolMOF-1 , which is among the highest performance of NH2-UiO-66 based MOFs. Furthermore, Zr/Cu-ATA is an efficient catalyst that can generate 12.8 mmol of H2 in 2 h under visible light irradiation. The light absorption band of Zr/Cu-ATA shifted to the near-IR region and the presence of Cu-oxo clusters significantly narrowed the bandgap from 2.95 eV (Zr-ATA) to 1.93 eV (Zr/Cu-ATA). Other photo -electrochemical studies further confirmed that the high catalytic performance of Zr/Cu-ATA can be ascribed to optimized bandgap, facile charge transfer and availability of large number of active sites.