Electron Beam Irradiation-Induced Defects Enhance Pt-TiO2 Photothermal Catalytic Degradation in PAEs: A Performance and Mechanism Study

Phthalic acid esters (PAEs), ubiquitous semi-volatile organic compounds (SVOCs) in indoor environments, pose adverse effects on human health. However, their degradation mechanisms and pathways remain unclear. Herein, we developed an efficient photothermal catalyst by introducing defects (oxygen vacancies, O_Vs) on TiO₂ (P25) surfaces via electron beam irradiation technology with different irradiation doses (100, 300, 500, and 700 kGy). The TiO₂ with defects was employed as a support to prepare Pt-TiO₂ catalysts for the photothermal degradation of di (2-ethylhexyl) phthalate (DEMP) and dimethyl phthalate (DMP), two representative PAEs. TiO₂ pre-treated with a 300 kGy irradiation dose supported the Pt catalyst (Pt-Ti-P-300) and presented the optimal catalytic performance for DEMP and DMP degradation. Characterization results confirmed that O_Vs were successfully introduced to the catalysts. Meanwhile, O_Vs induced by electron beam irradiation expanded the light absorption range and improved the generation and separation of photogenerated carriers, which significantly enhanced the catalytic activity of the catalysts for PAE degradation. Importantly, the degradation mechanism and pathway of DMP were further explored by using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and gas chromatography-mass spectrometry (GC-MS). These findings provide important insights into the electron beam irradiation-mediated regulation of catalysts and the photothermal catalytic removal of PAEs in indoor environments.