Ce(III)‐Doped Mixed‐Valence Metal–Organic Frameworks Boosting Ligand‐To‐Metal Charge Transfer for Photooxidation of a Mustard‐Gas Simulant

Due to the high toxicity and potential threats to society, extensive efforts are devoted to developing catalysts for efficient photodegradation of mustard gas. Metal-organic frameworks (MOFs) are considered as promising candidates for photooxidation, but the limited charge separation efficiency of the pristine MOFs restricts their further applications. Herein, through a one-pot synthesis strategy, Ce(III) ions are incorporated in a Ti-based porphyrin MOF (DGIST-1), leading to a mixed-valence MOF with enhanced charge transfer efficiency. Thanks to the unique electronic structure of Ce(III) and redox ability of porphyrin ligands, the Ce(III)-doped MOF exhibits remarkable photodegradation ability toward the sulfur mustard-gas simulant with a short half-life (t_1/2 = 1.60 min) and, more importantly, a high turnover frequency (TOF = 2.08 s^-1), which is significantly outperformed the reported photocatalysts, even most of the noble metal-based photocatalysts. Mechanistic studies and theoretical calculations demonstrate that the introduction of Ce(III) can notably improve the charge transfer efficiency via ligand-to-metal charge transfer, thereby promoting the activation of O₂ to reactive oxygen species and the degradation of mustard-gas simulant.