Synergistic Upconversion and Molecular Imprinting in Flame-Made Yb/Nd Co-doped TiO2 for Targeted Photocatalytic Degradation of Tetracycline in Complex Water.

Conventional TiO2 photocatalysts are constrained by limited solar-light utilization and poor selectivity, which severely hinder their application in antibiotic wastewater treatment. Herein, we construct a Yb/Nd co-doped TiO2@molecularly imprinted polymer (YNT@MIP) system that integrates near-infrared upconversion luminescence with selective recognition to boost tetracycline (TC) degradation. Flame spray pyrolysis is employed to incorporate Yb3+ and Nd3+ ions, followed by interfacial coupling with a MIP shell layer, which narrows the apparent band gap to 2.17 eV. Upon 980 nm excitation, upconverted emission in the 465-660 nm range is generated and reabsorbed by TiO2, thereby enhancing charge-carrier production. The surface MIP shell, anchored via strong interfacial interactions, provides selective cavities, while its imprinted porous architecture mitigates electron screening and facilitates interfacial charge transfer. The optimized YNT@MIP achieves 93.1% TC degradation within 60 min under simulated sunlight, with a rate constant of 0.042 min-1 and 1.68 times that of the non-imprinted counterpart, exhibiting a selectivity factor as high as 3.31 in complex water. This synergistic strategy offers a novel viable route toward efficient and selective photocatalytic water purification.