Visible‐Light‐Responsive 2D Cadmium–Organic Framework Single Crystals with Dual Functions of Water Reduction and Oxidation

The development of new metal–organic frameworks (MOFs) with dual functions of both water reduction and oxidation under visible‐light irradiation is highly desirable for promising solar water splitting, but is not yet reported. Herein, a cadmium‐based MOF (denoted as “Cd‐TBAPy”) single crystal with a 2D layered framework by employing 1,3,6,8‐tetrakis(p‐benzoic acid)pyrene (H 4 TBAPy) as an organic linker is reported, which exhibits good visible‐light absorption with edge of ≈600 nm. The Mott–Schottky (M–S) measurement and UV–vis analysis integrally reveal that the Cd‐TBAPy is an n‐type semiconductor with a bandgap of ≈2.15 eV whose conduction and valence band are estimated to be −0.05 and 2.10 eV, respectively. Together with loading of Pt or CoPi cocatalyst, the Cd‐TBAPy is active for both water reduction and oxidation in the presence of scavengers under visible‐light irradiation. Especially, the optimized apparent quantum efficiency for O 2 evolution reaches 5.6% at 420 nm, much higher than that of previous MOF‐based photocatalysts reported so far. This is thought to be the first MOF that functions as a photocatalyst for both water reduction and oxidation under visible light, demonstrating the intriguing future of MOF materials in solar‐to‐chemical energy conversion.