Engineering Full-Spectrum (UV–Vis–NIR) Photocatalytic Antibiotic Oxidation in Metal–Organic Frameworks via Dual-Ligand-to-Metal Charge Transfer

Tailoring the electronic structure of metal-organic frameworks (MOFs) has been recognized as a viable approach to promote the photocatalytic activity toward antibiotic oxidation. However, conventional single-ligand MOFs are plagued by notable drawbacks, such as inefficient spatial separation of photogenerated electron-hole pairs, transfer, and light harvesting, that are closely related to the ligand-to-metal charge transfer (LMCT) pathway. Herein, we report the design of a dual-ligand MOF (MY10) fabricated via the self-assembly of Eosin Y (EY) as a target ligand with the Cu-MOFs (Cu-ES)-based main framework. Endowed with a distinctive electronic structure and enhanced oxidative capability for ROS generation, MY10 realizes visible light-responsive antibiotic oxidation, a function that is absent in the pristine Cu-ES. In addition, the n-π* transition of carbonyl moieties within the MY10 framework exerts a beneficial impact in the near-infrared region, effectively boosting light absorption capacity and charge excitation efficiency. The charge carriers generated on MY10 can specifically transform molecular oxygen into reactive oxygen species (ROS), which further trigger and facilitate the activation of inert C-H bonds, as demonstrated in antibiotic oxidation reactions. MY10 delivers outstanding tetracycline (TC) degradation efficiencies: 88.7% under UV irradiation, 77.9% under visible light, 49.9% at 730 nm, and 89.5% under full-spectrum light, coupled with excellent long-term stability. This remarkable enhancement in photocatalytic antibiotic oxidation performance stems from the efficient light harvesting and improved charge dynamics induced by the unique dual-ligand-induced ligand-to-metal charge transfer (DLMCT) process. The accelerated charge transfer efficiency mediated by DLMCT is validated through a suite of characterizations, including photoelectrochemical measurements, spectroscopic analyses, and surface photovoltage tests. This study presents a novel strategy for constructing dual-ligand MOFs by incorporating a DLMCT process, thus unlocking the application of ultraviolet-visible-near-infrared light in C-H bond activation.