Abstract Supercritical hydrothermal synthesis of nanosized metal oxides is of great interest for scholars due to its one-pot and readily realizing commercial production process. Hydrothermal synthesis of nanosized TiO2 in subcritical and supercritical water was investigated with different reaction temperatures (250–450°C), time (3–10 min), precursor species (Ti(SO4)2, TiCl4), and the addition of a surfactant (CH3(CH2)5NH2). TiO2 synthesized under supercritical state has a higher degree of crystallinity when compared with TiO2 obtained from subcritical state, which is attributed to a higher reaction rate. Extending reaction time from 3 to 10 min leads to the growth of crystal and broader size distribution (36.66 ± 8.5 nm). More uniform products can be obtained when Ti(SO4)2 acting as the precursor compared with TiCl4 being the precursor. The application of surfactant CH3(CH2)5NH2 in the synthesis makes chemical bonding between the particle surface and organic ligand. It affects the growth direction of TiO2 crystal; as a result, rod-like TiO2 crystal is obtained.

中文翻译：

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超临界水中一锅法合成纳米二氧化钛

摘要 纳米金属氧化物的超临界水热合成因其一锅法和易于实现商业化生产工艺而受到学者们的极大关注。在不同的反应温度（250-450°C）、时间（3-10 分钟）、前体物质（Ti(SO4)2、TiCl4）和添加表面活性剂的条件下，研究了在亚临界和超临界水中水热合成纳米尺寸的 TiO2 (CH3(CH2)5NH2)。与亚临界状态下合成的 TiO2 相比，超临界状态下合成的 TiO2 具有更高的结晶度，这归因于更高的反应速率。将反应时间从 3 分钟延长到 10 分钟会导致晶体的生长和更宽的尺寸分布 (36.66 ± 8.5 nm)。与作为前体的 TiCl4 相比，当 Ti(SO4)2 作为前体时可以获得更均匀的产品。表面活性剂CH3(CH2)5NH2在合成中的应用使颗粒表面与有机配体之间形成化学键。影响TiO2晶体的生长方向；结果得到棒状TiO2晶体。