The present study reports the development of a novel defective TiO2−x catalyst with oxygen vacancy (OV) which carries dual types of reaction sites for H2O2 activation. The performance of this catalyst on the degradation of organic pollutants was evaluated using organic dyes [such as methyl orange, methylene blue, and rhodamine B (RhB)] as model pollutants. The defects in TiO2−x exhibited a wide pH working window (pH 2–9) for RhB degradation which is wider than that of traditional Fenton systems. Furthermore, this catalyst retained its high catalytic activity even after five cycles. It was confirmed that the surface OV and Ti3+ of TiO2−x served as the active sites for H2O2 activation while the oxygen vacancy promoted adsorption of the organic pollutants, thus enhancing the Fenton-like catalytic performance. The results are applicable to Fenton catalysts via surface engineering and can stimulate new opportunities for the optimization of defect-type Fenton catalysts.Graphic AbstractThis study, reports the defect of TiO2−x oxygen vacancy (OV) catalyst with oxygen vacancy (OV) which carries dual types of reaction sites for H2O2 activation. The performance of this catalyst on the degradation of organic pollutants was evaluated using organic dyes [such as methyl orange, methylene blue, and rhodamine B (RhB)] as model pollutants. The defects in TiO2−x exhibited a wide pH working window (pH 2–9) for RhB degradation which is wider than that of traditional Fenton systems. Figure shows the schematic of the reaction mechanism. First, H2O2 adsorbs on the TiO2−x surfaces; consequently, the OV and Ti3+ serve as the “Fenton-catalytic” center for H2O2 activation to produce ·OH radicals on the TiO2−x surface. Meanwhile, OV on TiO2−x surface is beneficial for the adsorbed organic pollutants. Because of the generated hydroxyl radical on the TiO2−x surface is very close to the adsorbed pollutant. As a result, the rapid reaction of in situ generated hydroxyl radical with the adsorbed organic pollutants on the TiO2−x surface giving rise to excellent Fenton-like catalytic performance. The proposed overall Fenton-like reaction mechanism on oxygen deficient TiO2−x catalyst.

中文翻译：

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具有双重反应位点的缺氧 TiO2−x 用于活化 H2O2 以降解有机污染物

本研究报告了一种具有氧空位 (OV) 的新型缺陷 TiO2-x 催化剂的开发，该催化剂带有用于 H2O2 活化的双重反应位点。使用有机染料[如甲基橙、亚甲蓝和罗丹明 B (RhB)] 作为模型污染物评估了该催化剂对有机污染物降解的性能。TiO2-x 中的缺陷对 RhB 降解表现出较宽的 pH 工作窗口（pH 2-9），比传统 Fenton 系统更宽。此外，该催化剂即使在五次循环后仍保持其高催化活性。证实TiO2-x的表面OV和Ti3+是H2O2活化的活性位点，而氧空位促进了有机污染物的吸附，从而提高了类芬顿催化性能。结果通过表面工程适用于芬顿催化剂，并可以激发优化缺陷型芬顿催化剂的新机会。 图形摘要本研究报告了带有氧空位（OV）的 TiO2−x 氧空位（OV）催化剂的缺陷H2O2 活化的双重反应位点。使用有机染料[如甲基橙、亚甲蓝和罗丹明 B (RhB)] 作为模型污染物评估了该催化剂对有机污染物降解的性能。TiO2-x 中的缺陷对 RhB 降解表现出较宽的 pH 工作窗口（pH 2-9），比传统 Fenton 系统更宽。图为反应机理示意图。首先，H2O2 吸附在 TiO2-x 表面；最后，OV 和 Ti3+ 作为 H2O2 活化的“芬顿催化”中心，在 TiO2-x 表面产生·OH 自由基。同时，TiO2-x 表面的 OV 有利于吸附有机污染物。因为在 TiO2-x 表面产生的羟基自由基非常接近吸附的污染物。结果，原位生成的羟基自由基与吸附在 TiO2-x 表面的有机污染物发生快速反应，从而产生了优异的类芬顿催化性能。在缺氧 TiO2-x 催化剂上提出的整体类芬顿反应机制。原位生成的羟基自由基与吸附在 TiO2-x 表面的有机污染物发生快速反应，从而产生优异的类芬顿催化性能。在缺氧 TiO2-x 催化剂上提出的整体类芬顿反应机制。原位生成的羟基自由基与吸附在 TiO2-x 表面的有机污染物发生快速反应，从而产生优异的类芬顿催化性能。在缺氧 TiO2-x 催化剂上提出的整体类芬顿反应机制。