液相剥离法制备超薄氧化钛纳米薄片

Chemical Liquid Phase Exfoliation of Ultrathin Titania Nanoflakes

自石墨烯问世以来,纳米薄片材料以其独特的二维结构和电学性能,被视为未来电子器件的优秀备选材料。其中,二维氧化钛纳米薄片在减薄至纳米厚度时仍具有高介电常数,是一种很好的绝缘材料,但较小的横向尺寸限制了其应用。采用晶体的高温熔融生长法和层状材料的化学液相剥离法相结合,制备了单层和薄层的氧化钛（Ti_（0.87）O_2^（0.52-））纳米薄片,并结合X射线衍射仪（XRD）、扫描电子显微镜（SEM）等材料分析手段对其制备工艺进行了优化。通过降低高温熔融生长过程中的降温速率减少了副产物的生成,从而提高了产物的纯度,并将生成前驱体钛酸盐（KTO）的尺寸由约20μm增大至约200μm。还通过控制化学液相剥离过程中TBAOH溶液的浓度得到了剥离效果更好的氧化钛纳米薄片,并利用能谱仪（EDS）和原子力显微镜（AFM）等分析了氧化钛纳米薄片的形貌和成分。还利用静电吸引将氧化钛纳米薄片拼接成大面积的纳米薄膜,并通过超声处理大大减小了拼接时样品的重叠和空白。

Nanoflakes were regarded as perfect candidates for future electron devices because of their unique two-dimensional（2 D）structures and electrical properties since graphene was prepared.2 D titania nanoflakes were excellent insulating materialswith high dielectric constant even when their thicknesses reduced to a few nanometers.However,its application was limited by small lateral size.Herein,we prepared mono-and few-layer titania nanoflakes via combining crystal growth at high temperature and chemical liquid phase exfoliation of materials with layered structure.And the synthesis process was optimized with the assistance of X-ray diffraction（XRD）and scanning electron microscope（SEM）.In particular,the K_（0.8）[Ti_（1.73）Li_（0.27）]O_4（KTO） samples were prepared in a higher efficiency and their sizes was broadened to 200 μm from 20 μm through suppressing the yield of by-product K_2Ti_6O_（13） by decreasing rate of temperature fall.The exfoliation of titania nanoflakes was optimized by controlling the concentration of TBAOH solution.Moreover,the morphology and component of as-prepared titania nanoflakes were investigated by energy dispersive spectroscope（EDS） and atomic force microscope（AFM） techniques.Titania nanoflakes could be assembled together to form a nanofilm with larger lateral size via electrostatic attraction and the overlap and vacancy could be reduced by ultrasonic treatment.