Platinum-enhanced amorphous TiO2-filled mesoporous TiO2 crystals for the photocatalytic mineralization of tetracycline hydrochloride

Highlights: • Construction of a 3D-sandwich-like structure. • Amorphous TiO₂ was successfully filled into the pores of the mesoporous TiO₂. • Surface area increased without increasing the shell thickness. • Hole transfer to the catalyst surface was enhanced. • Adsorption and mineralization of tetracycline hydrochloride were improved. -- Abstract: The adsorption ability and photoactivity of a photocatalyst largely determine the mineralization efficiency of antibiotics. Herein, aiming to enhance the adsorption and mineralization of antibiotics, we constructed a hierarchical porous core-shell structure by filling amorphous TiO₂ in the pores of Pt-doped mesoporous TiO₂ crystals (MCs). The physical–chemical properties of the prepared samples were investigated by surface photovoltage spectroscopy, X-ray photoelectron spectroscope, etc. Adsorption and photocatalysis experiments were conducted with tetracycline hydrochloride as the model antibiotic. Pt nanoparticles doped at the interface of the rutile-amorphous homojunction remarkably enhanced the built-in electric field. The enhanced electric field increased the hole transfer to the catalyst surface, and the Pt doping treatment promoted the growth of amorphous TiO₂ into the mesopores of the MCs. The optimization increased the surface area of the catalyst without increasing the thickness of the amorphous TiO₂ shell, thereby reducing the charge migration distance from the core–shell interface to the catalyst surface. The adsorption amount and mineralization efficiency of tetracycline hydrochloride for the porous core-shell composite were 6.7 and 3.8 times of those for MCs, respectively.