二维碳化钛纳米材料的改性及其电化学性能研究

发布时间：2018-04-12 10:05

本文选题：MXenes + Ti_3C_2　；参考：《陕西科技大学》2017年硕士论文

【摘要】：近期,二维过渡金属碳化物(MXenes)在能量储存应用中是一种富有前景的电极材料。作为MXenes家族最有前景的一员,Ti_3C_2作为有前景的电极材料得到了广泛研究,并应用于超级电容器。然而,由于其相对低的比表面积和电子导电性,多层Ti_3C_2表现出较差的容量性能。针对以上问题,为进一步提高Ti_3C_2的电化学性能,本论文进行了以下几方面的研究工作。(1)研究腐蚀时间对Ti_3C_2合成的影响,结果表明:腐蚀时间能够改变Ti_3C_2的形貌、表面官能团以及电化学性能等。腐蚀时间为216 h的Ti_3C_2(Ti_3C_2-216)在5 mV s-1下展现出118 F g-1的高比容量,而且其拥有良好的速率性能和循环稳定性。电化学性能的提高主要源于:高的碳含量提供更好的导电性和更快的电子传输,以及更大的比表面积提供更多电极与电解液的通道。这为制备更高性能的Ti_3C_2基纳米电极材料奠定了基础。(2)为进一步提高电极材料的比表面积,利用简单的原位水解和热处理方法,制备出TiO_2纳米颗粒修饰层状Ti_3C_2的纳米复合材料(TiO_2-Ti_3C_2)。结果表明:TiO_2-Ti_3C_2纳米复合材料在5 mV s-1下展现出143 F g-1的高比容量,和良好的循环稳定性。TiO_2纳米颗粒的引入可以提供更大的比表面积以提供更多的活性位点,提供额外电解液的扩散通道,和作为层间间距器防止片层的坍塌,协同地作用,从而导致TiO_2-Ti_3C_2纳米复合材料电化学性能的显著提高。这表明Ti O_2-Ti_3C_2可以作为一种高性能超级电容器的电极材料。(3)为增加材料的层间距和赝电容,利用简单的液相沉淀法和热处理过程制备出MnO_2纳米颗粒改性的Ti_3C_2基纳米复合材料(MnO_2-Ti_3C_2)。结果表明:MnO_2纳米颗粒能够增加Ti_3C_2的层间距,提供更多电荷存储空间。最终,MnO_2-Ti_3C_2纳米复合材料展现了优异的电容性能,在5 mV s-1时面积容量达到377 mF cm-2,及其高的速率性能,和良好循环稳定性。性能的改善主要源于层间距的扩大有助于更多的K+嵌入插层,和导电基体提供的更快的电子扩散。这表明MnO_2-Ti_3C_2纳米复合材料可为高性能超级电容器提供可能。(4)为进一步提高材料的导电性和赝电容,以尿素为氮源,通过简单的一步水热法制备了氮掺杂Ti_3C_2纳米片N-Ti_3C_2。结果表明:氮原子成功并均匀地掺杂进Ti_3C_2基体内。N-Ti_3C_2能够提供更高的比容量(在扫描速率为5 mV s-1时达到156 F g-1),和良好的速率性能和循环稳定性。N-Ti_3C_2电化学性能提高的主要原因是:导电性的增加;含氮基团提供的额外赝电容;晶面间距的扩大提供了更多K+的插层,协同地作用。这表明N-Ti_3C_2纳米材料可用作高性能超级电容器的电极材料。
[Abstract]:Recently, two dimensional transition metal carbide (MXenes) is a promising electrode material for energy storage.As the most promising member of the MXenes family, Ti3Cs2 has been widely studied as a promising electrode material and applied to supercapacitors.However, due to its relatively low specific surface area and electronic conductivity, multilayer Ti_3C_2 exhibits poor capacity performance.In order to further improve the electrochemical performance of Ti_3C_2, the following research work has been done in this thesis. The effect of corrosion time on the synthesis of Ti_3C_2 is studied. The results show that the corrosion time can change the morphology of Ti_3C_2.Surface functional groups and electrochemical properties.Tis _ 3C _ 2C _ 2C _ (2) C _ (2) C _ (2) T _ s _ (2) C _ (2) C _ (2) C _ (2) C _ (2) C _ (2) C _ (2) C _ (16) C _ (2) C _ (2) C _ (2) C _ (1)The improvement of electrochemical performance is mainly due to: higher carbon content provides better conductivity and faster electron transport, and larger specific surface area provides more channels between electrode and electrolyte.In order to further improve the specific surface area of electrode materials, TiO_2 nanoparticles modified layered Ti_3C_2 nanocomposites were prepared by in situ hydrolysis and heat treatment.The results show that the high specific capacity of 143F g ~ (-1) and good cyclic stability can be obtained by introducing TiO2-Ti3C2 nanocomposites at 5mV / s ~ (-1). The introduction of TiO-2 nanoparticles can provide a larger specific surface area to provide more active sites.Providing diffusion channels for additional electrolytes and acting as interlaminar spacers to prevent lamellar collapse and synergistic action, the electrochemical properties of TiO_2-Ti_3C_2 nanocomposites were significantly improved.This indicates that Ti O_2-Ti_3C_2 can be used as an electrode material for high performance supercapacitors to increase the interlayer spacing and pseudo-capacitance of the materials. Using simple liquid precipitation method and heat treatment process, the MnO_2 nano-particles modified Ti_3C_2 matrix nanocomposites, MNO _ 2-Ti _ 3C _ 2C _ 2, have been prepared by means of simple liquid phase precipitation method and heat treatment process.The results show that: MNO _ 2 nanoparticles can increase the interlayer spacing of Ti_3C_2 and provide more charge storage space.Finally, MNO _ 2-TiC _ 2 nanocomposites showed excellent capacitive properties, with an area capacity of 377mF / cm ~ (-2) at 5mV / s ~ (-1), and high rate performance and good cyclic stability.The improvement of the performance is mainly due to the increase of intercalation between the layers and the faster electron diffusion provided by the conductive matrix.The results show that the nitrogen atoms are successfully and uniformly doped into the Ti_3C_2 base. N-TiStat3Cs2 can provide a higher specific capacity (156F g -1 at a scanning rate of 5 MV s-1), and good rate performance and cyclic stability. N-Ti3C2 electrochemical performance is improved.The main reasons are: the increase of conductivity;The addition of pseudo-capacitors provided by nitrogen-containing groups and the expansion of crystal plane spacing provide more K intercalations and act synergistically.This indicates that N-Ti_3C_2 nanomaterials can be used as electrode materials for high performance supercapacitors.
【学位授予单位】：陕西科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;TM53

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