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

Abstract

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.