Amphoteric oxides can be challenging to produce in phase pure form due to their sensitivity to the pH of the reaction mixture. The high-pressure, high-temperature reaction conditions of hydrothermal processes make the pH difficult to control. Here we report a simple approach to obtain nanoparticles of amphoteric oxides, where cheap metal nitrate precursors are reacted in alcohol (2-propanol) water mixtures (25 vol%:75 vol%) to maintain a neutral pH under solvothermal conditions. Phase pure SnO nanoparticles were synthesized in a continuous flow solvothermal reactor at 250 °C, 300 °C, 350 °C and 400 °C with sizes ranging from 3 nm to 7 nm. The nanoparticles were characterized using powder X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy, Sn MAS NMR spectroscopy, Brunauer-Emmett-Teller nitrogen adsorption, UV–VIS, and as anode material in CR2032 Li-ion battery cells. To demonstrate generality, amphoteric oxides ZnO, BiO, CrO and γ-AlOOH were also synthesized.

中文翻译：

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通过 pH 控制的连续流动溶剂热合成制备两性 SnO2 纳米粒子


由于两性氧化物对反应混合物的 pH 值敏感，因此以纯相形式生产两性氧化物可能具有挑战性。水热过程的高压、高温反应条件使得pH值难以控制。在这里，我们报告了一种获得两性氧化物纳米颗粒的简单方法，其中廉价的金属硝酸盐前体在醇（2-丙醇）水混合物（25 vol%:75 vol%）中反应，以在溶剂热条件下保持中性pH。在连续流溶剂热反应器中，在 250 °C、300 °C、350 °C 和 400 °C 下合成了相纯 SnO 纳米颗粒，尺寸范围为 3 nm 至 7 nm。使用粉末 X 射线衍射、透射电子显微镜、能量色散 X 射线光谱、拉曼光谱、Sn MAS NMR 光谱、Brunauer-Emmett-Teller 氮吸附、UV-VIS 表征纳米颗粒，并作为 CR2032 Li- 中的阳极材料。离子电池。为了证明通用性，还合成了两性氧化物 ZnO、Bi2O、Cr2O 和 γ-AlOOH。