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Chemically bonded Z-scheme ZnSnO 3 /AgI composites rich in oxygen vacancies (OVs) and Lewis acid sites were prepared successfully and showed excellent photocatalytic activities. Especially, ZnAg-2 degraded 96.1% tetracycline under visible light irradiation for 15 min. OVs contributed to Lewis acid sites production and interfacial chemical bonds formation through weakening the metal−O bonding. Lewis acid sites favored the adsorption of electron-rich tetracycline. Interfacial chemical bonds together with Z-scheme structure accelerated electron transfer and retained the high redox ability of ZnSnO 3 and AgI. OVs contributed to singlet oxygen (1O 2) production through facilitating the energy transfer from triplet exciton to O 2. ZnSnO 3 /AgI composites possess good reusability and show great practical application potential. Based on ROSs generation and photoreduction experiment, the photocatalytic mechanism of the ZnAg composites was proposed. The possible degradation pathway was deduced and the biological toxicity was evaluated based on detected degradation intermediates. This work highlights the significant roles of OVs, Lewis acid sites, and chemical bonding in improving the photocatalytic activity of Z-scheme composites and provides new insight into designing high efficient photocatalysts. [Display omitted] • ZnAg-2 composite degraded 96.1% tetracycline under visible light for 15 min. • OVs helped form interfacial chemical bonds and produce 1O 2. • More Lewis acid sites in ZnAg-2 contributed to tetracycline adsorption. • The interfacial chemical bonds acted as "channels" to promote charge transfer. • Z-scheme structure and OVs boosted ROSs generation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Z-scheme InVO 4 /CuBi 2 O 4 /BiVO 4 composites were fabricated with hydrothermal synthesis. • Interfacial Bi O bonds boosted the charge transfer from InVO 4 and BiVO 4 to CuBi 2 O 4. • O vacancies brought by orthovanadates enhanced 1O 2 production through energy transfer. • InVO 4 /CuBi 2 O 4 /BiVO 4 showed good photocatalytic activity for tetracycline degradation. • The composite had good reusability, stability, and performed well in natural water. Dual Z-scheme InVO 4 /CuBi 2 O 4 /BiVO 4 (CuInBi) composites with rich oxygen vacancies and chemical bonds at the heterojunction interfaces were fabricated, for the first time, through hydrothermal method with post annealing treatment, in which CuBi 2 O 4 acts as a bridge to connect InVO 4 and BiVO 4. The as-prepared composites exhibited superior photocatalytic activity compared with the individual semiconductors. Specifically, the degradation rate of tetracycline (20 mg/L) in the presence of CuInBi-1 (1.0 g/L) was up to 5.4, 2.8, and 3.1 times faster than those in the presence of CuBi 2 O 4 , InVO 4 , and BiVO 4 , respectively. The enhanced photocatalytic performance could be partially attributed to the good light absorption of CuBi 2 O 4 , which broadens the visible light response of the InVO 4 /CuBi 2 O 4 /BiVO 4 composites. Meanwhile, the interfacial chemical bonds in the dual Z-scheme heterojunction help accelerate charge separation and maintain strong redox activity. In addition, the oxygen vacancies, induced mainly by the low-valent vanadium atoms, facilitate the production of singlet oxygen (1O 2) through energy transfer, which easily attacks the electron-rich groups, including phenolic group, dimethylamino group, amine group, and double bonds, in tetracycline. The InVO 4 /CuBi 2 O 4 /BiVO 4 composite exhibited excellent reusability and stability, and performed well in photocatalytic degradation of tetracycline in river water and under natural sunlight, demonstrating great potential for practical application. The probable photocatalytic mechanism of InVO 4 /CuBi 2 O 4 /BiVO 4 composite was proposed according to the results of density functional theory (DFT) calculations, and the reactive oxygen species (ROSs) and major degradation intermediates detected in the photocatalytic system. This work demonstrates the important roles of oxygen vacancies and interfacial chemical bonds in boosting the photocatalytic activity of Z-scheme heterojunctions and provides a reference for the construction of high-activity photocatalysts for efficient degradation of antibiotics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hollow tubular In 2 O 3 /AgI photocatalysts with oxygen vacancies were synthesized. • A BIEF with e- flowing from AgI to In 2 O 3 helps the formation of Z-scheme structure. • In 2 O 3 /AgI (2:1, molar) performed well as a photocatalyst for tetracycline degradation. • 1O 2 , h+, •O 2 −, and •OH were the key reactive species in the photocatalytic system. • In 2 O 3 /AgI photocatalysts exhibited excellent structural stability and reusability. A novel In 2 O 3 /AgI heterojunction, which has a hollow tubular structure with AgI particles distributed evenly on the outer and inner surfaces of In 2 O 3 microtubes, was fabricated from annealing of AgI adhered to MIL-68(In). The as-prepared heterojunction exhibited much higher photocatalytic activity towards tetracycline degradation compared to In 2 O 3 and AgI. The presence of InAg-1 (1.0 g/L), which has a In 2 O 3 :AgI mole ratio of 2:1, could achieve 98.4% removal of tetracycline (20 mg/L) from the solution phase under visible light illumination in 10 min, and it had excellent reusability and stability. The In 2 O 3 /AgI heterojunction also exhibited excellent performance in photocatalytic degradation of tetracycline in different types of water matrices and under natural sunlight illumination, demonstrating its potential in practical application. The superior photocatalytic activity of InAg-1 is attributed to the heterojunction formation and generation of oxygen vacancies (OVs), which improve the separation efficiency of photoinduced e−-h+ pairs. Meanwhile, the built-in electric field (BIEF) formed with e- flowing from AgI to In 2 O 3 , which is confirmed by density functional theory calculations, helps the formation of a Z-scheme, instead of type II, heterojunction between In 2 O 3 and AgI. Results of radical trapping experiments and electron spin resonance spectra reveal that 1O 2 , h+, •O 2 −, and •OH were the key reactive species involved in the photocatalytic degradation process. These findings indicate that Z-scheme photocatalysts with OVs could efficiently activate molecular oxygen and thus have excellent photocatalytic activity towards degradation of organic pollutants. [ABSTRACT FROM AUTHOR]