2D metal azolate framework for efficient CO₂ photoreduction

Visible-light-driven conversion of CO₂ into value-added fuel is a clean and renewable technology to retard global warming and address energy shortages. Two-dimensional metal-azolate frameworks (2D MAFs) have recently received tremendous attention as CO₂ photoreduction-related catalysts due to their specific electron transport pathways, highly exposed surface-active sites, and tailorable light-absorption abilities. However, the research on 2D MAFs for efficient CO₂ photoconversion is still at the early stage. Herein, a novel 2D MAFs (compound 1) was designed by self-assembly of tetra-(4-tetrazole-phenyl)ethylene (H₄TTPE) and cobalt for CO₂ photoreduction. As a comparison, three-dimensional (3D) compound 2 was also constructed using a similar synthesis process. The experimental results of heterogeneous photocatalysis show that the photoreduction performance of 2D compound 1 is obviously better than that of 3D compound 2, exhibiting an extremely high CO production rate (11.56 mmol g⁻¹ h⁻¹) in 3 h, which is 6.0-fold higher than that of compound 2 (1.94 mmol g⁻¹ h⁻¹) under the same conditions. This performance advantage stems from the unique 2D structure of compound 1, which not only possesses an energy level conducive to CO₂ reduction but also facilitates efficient electron-hole separation throughout the CO₂ photo-reduction process. This work paves the way for the design of 2D MAFs photocatalysts tailored for efficient CO₂ photoconversion.