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[Display omitted] • Activated carbon modified TiO 2 /Bi 2 O 3 adsorbent was prepared by a one-pot hydrothermal method. • Low temperature calcination (280 °C) led to high surface area (188.49 m2/g) of TiO 2 /Bi 2 O 3 /AC. • The integrated adsorbent/photocatalyst system promoted high removal efficiency of organic pollutants. • The efficient adsorption and photo-regeneration mechanism of tetracyclines were detailed. Considerable endeavors have focused on tightly combining adsorption with photocatalysis in designing composite materials for environmental pollution treatment. Recent advances in coupling titanium dioxide/bismuth trioxide (TiO 2 /Bi 2 O 3) with activated carbon (AC) show significantly enhanced photocatalytic performance but face critical limitations including low adsorption capacity and multi-step synthesis. In this work, we introduce a one-pot synthesis of activated carbon modified TiO 2 /Bi 2 O 3 composite materials (TiO 2 /Bi 2 O 3 /AC). Thanks to the integrated adsorbent/photocatalyst system, TiO 2 /Bi 2 O 3 /AC shows a drastically enhanced removal efficiency for sulfamethazine (>81%), far beyond the corresponding value of the reported AC/TiO 2 /Bi 2 O 3 adsorbent (<40%). Notably, the removal rates of other typical pollutants including tetracyclines, methyl orange, and rhodamine B are as high as >98%. Furthermore, TiO 2 /Bi 2 O 3 /AC obtains >80% of its adsorption rate for the fifth cycle after simple photo-regeneration without any other post-treatments. Kinetic analysis and photoelectric characterization are carried out to provide insight into adsorption mechanism. Therefore, this work demonstrates a considerable potential to design and construct other multifunctional adsorbents with advanced performance. [ABSTRACT FROM AUTHOR]

TiO2 has been widely used as a photocatalyst and an electrode material toward the photodegradation of organic pollutants and electrochemical applications, respectively. However, the properties of TiO2 are not enough up to meet practical needs because of its intrinsic disadvantages such as a wide bandgap and low conductivity. Incorporation of carbon into the TiO2 lattice is a promising tool to overcome these limitations because carbon has metal-like conductivity, high separation efficiency of photogenerated electron/hole pairs, and strong visible-light absorption. This review would describe and discuss a variety of strategies to develop carbon-doped TiO2 with enhanced photoelectrochemical performances in environmental, energy, and catalytic fields. Emphasis is given to highlight current techniques and recent progress in C-doped TiO2-based materials. Meanwhile, how to tackle the challenges we are currently facing is also discussed. This understanding will allow the process to continue to evolve and provide facile and feasible techniques for the design and development of carbon-doped TiO2 materials. [ABSTRACT FROM AUTHOR]

Combining heterojunction with advanced structures is a promising tool to enhance the photoelectrochemical performance of semiconductor photocatalysts for environmental remediation. Herein, a novel multi-heterojunction TiO 2 @Bi 2 O 3 (MHTB) hollow photocatalyst is successfully constructed by loading Bi 2 O 3 nanoparticles on the surface of inner TiO 2 and outside of TiO 2 shell. Photoelectrochemical characterizations show that the formation of multiple heterojunctions at the TiO 2 @Bi 2 O 3 interfaces facilitates faster separation and transfer of photoinduced charge carriers than that of conventionally reported p-n heterojunction photocatalysts. Because of the separated two layers of Bi 2 O 3 and unique hollow structure, the photocatalytic performance of MHTB is significantly improved, leading to excellent photo-degradation rate constant (k = 0.0165 min−1) for the degradation of levofloxacin, which approaches 1.5-fold and 2.6-fold increase than that of TiO 2 @Bi 2 O 3 @TiO 2 (n-p-n heterojunction) and TiO 2 @Bi 2 O 3 (n-p heterojunction), respectively. Notably, the MHTB photocatalyst exhibits an excellent anti-interference capability for the interference of environmental factors. Moreover, the photocatalytic activity, crystal structure, and bonding energy of MHTB photocatalyst remain unchanged after being used several times, indicating an excellent stability. Therefore, this finding opens a new door to develop highly active photocatalysts with multiple heterojunctions for efficient pollutant removal and environmental remediation. [Display omitted] • Multi-heterojunction TiO 2 @Bi 2 O 3 photocatalyst (MHTB) was prepared for the first time. • MHTB drove the efficient degradation (>98%) and mineralization (92.6%) of levofloxacin under visible light. • Multi-heterojunction and hollow structure contributed to the degradation of levofloxacin. • The degradation pathway and mechanism of levofloxacin was proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • The p-n heterojunction Bi 2 O 3 /Ti3+-TiO 2 photocatalyst was reported by a facile method. • The Bi 2 O 3 /Ti3+-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 Ti3+ 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 Ti3+ 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. [ABSTRACT FROM AUTHOR]