Photosensitizing Metal–Organic Layers for Efficient Sunlight-Driven Carbon Dioxide Reduction

Abstract

Metal–organic layers (MOLs), a free-standing monolayer version of two-dimensional metal–organic frameworks (MOFs), have emerged as a new class of 2D materials for many potential applications. Here we report the design of a new photosensitizing MOL, Hf 12 -Ru, based on Hf 12 secondary building units (SBUs) and [Ru(bpy) 3 ] 2+ (bpy = 2,2′-bipyridine) derived dicarboxylate ligands. After modifying the SBU surface of Hf 12 -Ru with M(bpy)(CO) 3 X (M = Re and X = Cl or M = Mn and X = Br) derived capping molecules through carboxylate exchange reactions, the resultant Hf 12 -Ru-Re and Hf 12 -Ru-Mn MOLs possess both [Ru(bpy) 3 ] 2+ photosensitizers and M(bpy)(CO) 3 X catalysts for efficient photocatalytic CO 2 reduction. The proximity of the MOL skeleton to the capping ligands (1–2 nm) facilitates electron transfer from the reduced photosensitizer [Ru(bpy) 3 ] + to M I (bpy)(CO) 3 X (M = Re, Mn) catalytic centers, resulting in CO 2 reduction turnover numbers of 8613 under artificial visible light and of 670 under sunlight. MOLs thus represent a novel platform to assemble multifunctional materials for studying artificial photosynthesis.