Nowadays, an increasing discharge of oxyanions to the natural environment has been attracting worldwide attention. TiO2-based photocatalysis is regarded as one of the most promising technologies for the conversion of toxic oxyanions (such as chromate, nitrate, nitrite, bromate, perchlorate and selenate) to harmless and/or less toxic substances in contaminated waters. Various types of TiO2-based catalysts have been developed, and each of them exhibits its own advantages in catalytic reduction of oxyanions. However, the application of these nanostructured TiO2 in real water bodies remains a challenge, with limitations associated with sunlight harvesting abilities, production costs, reuse stability and exposure risks. Herein, we aim to present a critical review on reported TiO2-based photocatalytic reduction of aqueous oxyanions, provide a comprehensive understanding of the possible reaction pathways of formed active species, and evaluate the reduction performance of different types of TiO2-based catalysts. In addition, the impact of operating parameters (such as solution pH, temperature, dissolved oxygen and coexisting substances) on catalytic reduction performance is discussed. Furthermore, the perspectives of TiO2-based photocatalytic reduction of oxyanions are also proposed.

中文翻译：

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用于光催化还原水性含氧阴离子的基于TiO2的催化剂：最新技术和未来前景。

如今，越来越多的氧阴离子向自然环境排放已引起全世界的关注。基于TiO2的光催化被认为是将有毒含氧阴离子（例如铬酸根，硝酸根，亚硝酸根，溴酸根，高氯酸根和硒酸根）转化为受污染水中无害和/或毒性较小的物质的最有前景的技术之一。已经开发出各种类型的基于TiO 2的催化剂，并且它们各自在催化还原氧阴离子方面显示出自己的优势。然而，这些纳米结构的TiO2在实际水体中的应用仍然是一个挑战，其局限性在于阳光的收集能力，生产成本，再利用稳定性和暴露风险。在此，我们旨在对已报道的基于TiO2的光催化还原含氧阴离子进行严格的综述，提供了对形成的活性物种可能的反应途径的全面理解，并评估了不同类型的TiO2基催化剂的还原性能。此外，还讨论了操作参数（例如溶液的pH，温度，溶解氧和共存物质）对催化还原性能的影响。此外，还提出了基于TiO 2的光催化还原氧阴离子的观点。