Orchestrating Proton-Coupled Electron Transfer in Atomically Wired SubPc-CuBTC-NH2 Heterostructure for Panchromatic Photocatalytic Cascade Reactions

Abstract Proton-coupled electron transfer (PCET) is pivotal for photocatalytic H2O2 synthesis yet remains constrained by the slow kinetics of water oxidation, which impedes synchronous proton supply. Herein, a triple-site photocatalyst (SubPc1-CuBTC-NH2) was constructed where thermodynamically unfavorable water oxidation is supplanted by efficient tetracycline oxidation, thereby redirecting the PCET pathway. The covalent amide bridge functions as a dual channel for electron transfer and proton relay, reducing the proton-transport activation energy by 57% and the electron-transfer barrier by 35%, compared to pristine CuBTC-NH2. Under simulated sunlight, the composite achieves an H2O2 production rate of 2091.5 μmol·g−1·h−1, representing a 7.5-fold enhancement over the pristine CuBTC-NH2. Coupling with tetracycline degradation further elevates the H2O2 yield to 5517.4 μmol·g−1·h−1 while enabling >99.8% pollutant removal. Mechanistic insights reveal that Cu sites oxidize pollutants to release protons, the amide bridge facilitates interfacial electron and proton transport, and the SubPc1 macrocycle selectively reduces O2 to H2O2 through a synchronized PCET process. This study illustrates how covalent interface engineering can precisely program proton-electron spatiotemporal dynamics, establishing a material paradigm for efficient artificial photosynthesis beyond conventional water-oxidation limitations.