In recent years, hafnium oxide (HfO₂) has gained increasing interest because of its high dielectric constant, excellent thermal stability, and high band gap. Although HfO₂ bulk and film materials have been prepared and well-studied, HfO₂ fibers, especially hollow fibers, have been less investigated. In this study, we present a facile preparation method for HfO₂ hollow fibers through a unique integration of the sol–gel process and electrospinning technique. Initially, polystyrene (PS) fibers are fabricated by using electrospinning, followed by dipping in a HfO₂ precursor solution, resulting in HfO₂-coated PS fibers. Subsequent thermal treatment at 800 °C ensures the selective pyrolysis of the PS fibers and complete condensation of the HfO₂ precursors, forming HfO₂ hollow fibers. Scanning electron microscopy (SEM) characterizations reveal HfO₂ hollow fibers with rough surfaces and diminished diameters, a transformation attributed to the removal of the PS fibers and the condensation of the HfO₂ precursors. Our study also delves into the influence of precursor solution molar ratios, showcasing the ability to achieve smaller HfO₂ fiber diameters with reduced precursor quantities. Validation of the material composition is achieved through thermogravimetric analysis (TGA) and energy-dispersive spectroscopy (EDS) mapping. Additionally, X-ray diffraction (XRD) analysis provides insights into the crystallinity of the HfO₂ hollow fibers, highlighting a higher crystallinity in fibers annealed at 800 °C compared with those treated at 400 °C. Notably, the HfO₂ hollow fibers demonstrate a water contact angle (WCA) of 38.70 ± 5.24°, underscoring the transformation from hydrophobic to hydrophilic properties after the removal of the PS fibers. Looking forward, this work paves the way for extensive research on the surface properties and potential applications of HfO₂ hollow fibers in areas such as filtration, energy storage, and memory devices.

中文翻译：

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空心氧化铪 (HfO2) 纤维：有效结合溶胶-凝胶、静电纺丝和热降解途径


近年来，氧化铪（HfO ₂ ）因其高介电常数、优异的热稳定性和高带隙而受到越来越多的关注。尽管HfO ₂块状和薄膜材料已被制备并得到充分研究，但HfO ₂纤维，特别是中空纤维的研究较少。在这项研究中，我们通过溶胶-凝胶工艺和静电纺丝技术的独特结合，提出了一种简便的 HfO ₂中空纤维制备方法。最初，通过使用静电纺丝来制造聚苯乙烯(PS)纤维，然后浸入HfO ₂前体溶液中，产生HfO ₂涂覆的PS纤维。随后在 800 °C 的热处理确保 PS 纤维的选择性热解和 HfO ₂前驱体的完全冷凝，形成 HfO ₂中空纤维。扫描电子显微镜（SEM）表征显示HfO ₂中空纤维具有粗糙的表面和减小的直径，这种转变归因于PS纤维的去除和HfO ₂前体的缩合。我们的研究还深入研究了前驱体溶液摩尔比的影响，展示了通过减少前驱体用量实现更小的 HfO ₂纤维直径的能力。通过热重分析 (TGA) 和能量色散光谱 (EDS) 绘图来验证材料成分。此外，X 射线衍射 (XRD) 分析提供了对 HfO ₂中空纤维结晶度的深入了解，突显出在 800 °C 下退火的纤维比在 400 °C 下处理的纤维具有更高的结晶度。 值得注意的是，HfO ₂中空纤维的水接触角（WCA）为38.70 ± 5.24°，强调了去除PS纤维后从疏水性到亲水性的转变。展望未来，这项工作为HfO ₂中空纤维的表面特性和在过滤、能量存储和存储设备等领域的潜在应用的广泛研究铺平了道路。