Novel p-n heterojunction Bi2O3/Ti3+-TiO2 photocatalyst enables the complete removal of tetracyclines under visible light

Abstract

• The p-n heterojunction Bi 2 O 3 /Ti 3+ -TiO 2 photocatalyst was reported by a facile method. • The Bi 2 O 3 /Ti 3+ -TiO 2 enabled the complete removal (100%) of tetracyclines under visible light. • The effect of environmental factors on the photodegradation of tetracyclines was detailed. • The mechanism on photodegradation was analyzed through LC–MS spectrum. The search for a highly active visible-light photocatalyst toward the complete degradation of antibiotic residuals remains a challenging task due to the fast emergence of antibiotic resistance. To address the problem, we explore a novel p-n heterojunction visible-light photocatalyst by coupling a p-type Bi 2 O 3 with an n-type Ti 3+ self-doped TiO 2 porous material. The as-synthesized photocatalyst exhibits a narrowed bandgap (~2.89 eV) and enhanced visible-light absorption, leading to the complete degradation (100%) of antibiotics under visible light irradiation (λ > 420 nm) and excellent recyclability (98%) because of the synergistic effect of Ti 3+ self-doping and p-n heterojunction. The results effectively work out the challenging task of the incomplete removal of tetracyclines over almost all of the reported visible-light photocatalysts. Additionally, the effects of antibiotics mixture, pH value, inorganic ions, water matrix, and outdoor light on the degradation of tetracyclines were also detailed. Especially, the transformation pathways and degradation mechanism of tetracycline were revealed in depth via trapping experiments and photoelectrochemical characterizations. Therefore, this work provides a new insight in exploring excellent photocatalysts to realize the complete removal of other refractory organic pollutants under visible light.