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Insights into formation of anatase TiO2 nanoparticles from peroxo titanium complex degradation under microwave-assisted hydrothermal treatment
Ceramics International ( IF 5.1 ) Pub Date : 2019-12-01 , DOI: 10.1016/j.ceramint.2019.07.345
Vagner R. de Mendonça , Osmando F. Lopes , Waldir Avansi , Raul Arenal , Caue Ribeiro

Abstract Several methods for the synthesis of anatase TiO2 have been reported in the literature. In particular, the microwave-assisted hydrothermal crystallization of Ti-peroxocomplexes has enabled the phase and morphological control of TiO2 nanoparticles by adjusting the synthesis conditions, such as pH, time and temperature, with significant increase in the reaction rate compared to the conventional sol-gel techniques. In this paper, we uncover the mechanism involved in the formation of anatase TiO2 nanoparticles from the Ti-peroxo complex precursor route. Structural characterizations (XRD, Raman, TEM and XANES) revealed that the Ti-peroxo complex precursor exhibits a titanate-like structure, comprised of bulk NH4+ ions and surface peroxo groups. The NH4+ ions release during hydrothermal treatment is determining on the anatase TiO2 nanoparticle formation, which occurs concomitantly with the decomposition of peroxogroups. UV-induced dye photodegradation tests involving the Ti-peroxo complex precursor and TiO2 nanoparticles showed that the precursor is not able to form hydroxyl radicals that are the main chemical species responsible for the dye photodegradation, despite the presence of peroxo groups at its surface. The results herein highlight the mechanism involved in the formation of anatase TiO2 nanoparticles, which could assist in the development of new synthesis approaches based on Ti-peroxocomplex precursors.

中文翻译:

微波辅助水热处理下过氧化钛络合物降解形成锐钛矿TiO2纳米颗粒的见解

摘要 文献中报道了几种合成锐钛矿型TiO2的方法。特别是,Ti-过氧化物络合物的微波辅助水热结晶通过调节合成条件(如 pH、时间和温度)实现了 TiO2 纳米粒子的相和形态控制,与传统溶胶相比,反应速率显着提高。凝胶技术。在本文中,我们揭示了从 Ti-peroxo 复合前驱体路线形成锐钛矿 TiO2 纳米颗粒的机制。结构表征(XRD、拉曼、TEM 和 XANES)表明,Ti-peroxo 复合物前体表现出类似钛酸盐的结构,由大量 NH4+ 离子和表面过氧基团组成。水热处理过程中释放的 NH4+ 离子决定了锐钛矿 TiO2 纳米颗粒的形成,这与过氧基团的分解同时发生。涉及钛-过氧复合物前体和 TiO2 纳米颗粒的紫外线诱导染料光降解测试表明,尽管其表面存在过氧基团,但前体无法形成羟基自由基,而羟基自由基是导致染料光降解的主要化学物质。本文的结果突出了锐钛矿 TiO2 纳米粒子形成所涉及的机制,这有助于开发基于 Ti-过氧化物复合物前体的新合成方法。涉及 Ti-peroxo 复合物前体和 TiO2 纳米颗粒的 UV 诱导染料光降解测试表明,尽管其表面存在过氧基团,但前体无法形成羟基自由基,而羟基自由基是导致染料光降解的主要化学物质。本文的结果突出了锐钛矿 TiO2 纳米粒子形成所涉及的机制,这有助于开发基于 Ti-过氧化物复合物前体的新合成方法。涉及 Ti-peroxo 复合物前体和 TiO2 纳米颗粒的 UV 诱导染料光降解测试表明,尽管其表面存在过氧基团,但前体无法形成羟基自由基,而羟基自由基是导致染料光降解的主要化学物质。本文的结果突出了锐钛矿 TiO2 纳米粒子形成所涉及的机制,这有助于开发基于 Ti-过氧化物复合物前体的新合成方法。
更新日期:2019-12-01
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