Rational Design and Synthesis of a Metal–Organic Framework Featuring Cu(I)–Carbon Bonds for Enhanced Artificial Photosynthesis

The development of a stable and highly efficient artificial photosynthetic system without the need for additional electron sacrificial agents has long been a pursuit but remains highly challenging. Here, we designed and synthesized a novel metal-organic framework (MOF), Cu-TEPA (TEPA = tris(4-ethynylphenyl)amine), by connecting triphenylamine and Cu(I) ions via metal-carbon (M-C) bonds for artificial photosynthesis. Cu-TEPA showed excellent stability in pH = 0 or 14 aqueous solutions for over 12 h. Interestingly, using water as the electron donor, Cu-TEPA demonstrated remarkable performance in the overall artificial photosynthetic reaction, achieving a CO yield of 86.0 μmol g^-1 h^-1 with nearly 100% selectivity and an O₂ evolution rate of 43.9 μmol g^-1 h^-1, maintaining performance after five cycles. Mechanistic studies reveal that triphenylamine acts as both a photosensitizer and water oxidation catalyst, while Cu(I) reduces CO₂ to CO. Therefore, the superior performance of Cu-TEPA can be attributed to the excellent photosensitivity of triphenylamine, the high catalytic activity of Cu(I), and the more stable and conductive M-C bonds between the organic ligands and metal ions.