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 <i>n</i>-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.