A novel InO/AgI heterojunction, which has a hollow tubular structure with AgI particles distributed evenly on the outer and inner surfaces of InO 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 InO and AgI. The presence of InAg-1 (1.0 g/L), which has a InO: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 InO/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 InO, which is confirmed by density functional theory calculations, helps the formation of a Z-scheme, instead of type II, heterojunction between InO and AgI. Results of radical trapping experiments and electron spin resonance spectra reveal that O, h, •O, 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.

中文翻译：

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具有氧空位的直接 Z 型 In2O3/AgI 异质结可有效激活分子氧并增强四环素的光催化降解

通过将AgI粘附到MIL-68(In)上进行退火，制备了一种新型的InO/AgI异质结，该异质结具有中空管状结构，AgI颗粒均匀分布在InO微管的外表面和内表面上。与 InO 和 AgI 相比，所制备的异质结对四环素降解表现出更高的光催化活性。 InAg-1 (1.0 g/L) 的 InO:AgI 摩尔比为 2:1，在可见光照射下，10 分钟内可以实现 98.4% 的四环素 (20 mg/L) 从溶液相中去除，并且具有优异的可重用性和稳定性。 InO/AgI异质结在不同类型的水基质和自然阳光照射下对四环素的光催化降解也表现出优异的性能，展示了其实际应用的潜力。 InAg-1优异的光催化活性归因于异质结的形成和氧空位（OV）的产生，从而提高了光诱导电子对的分离效率。同时，密度泛函理论计算证实，e从AgI流向InO时形成的内建电场（BIEF）有助于InO和AgI之间形成Z型异质结，而不是II型异质结。自由基捕获实验和电子自旋共振光谱的结果表明，O、h、•O和•OH是参与光催化降解过程的关键活性物质。这些发现表明，带有OV的Z型光催化剂可以有效地活化分子氧，从而对有机污染物的降解具有优异的光催化活性。