Ti3C2和Ti3CN MXenes的制备、表征及其超级电容特性研究

Preparation, Characterization and Supercapacitor Properities of MXenes Ti3C2 and Ti3CN

甄莉

11749040

硕士

物理学

王善民

2019-05-14

2019-07-10

哈尔滨工业大学

深圳

二维MXene是一种新型二维材料，通过对MAX相原材料的刻蚀制备得到，自从被制备出来便引起了研究者的广泛关注。Ti3C2与Ti3CN是典型的两种MXene，具有类似石墨烯的二维片层状结构，片层厚度只有几个原子厚且具有稳定性好、比表面积高和载流子迁移率高等优点，被视为可以作为碳二维材料的替代品，可以作为储能材料应用为超级电容器的电极材料。超级电容器能量密度高，循环寿命长，安全无污染，在目前的新能源领域有着广泛的应用前景。目前Ti3C2这种MXene的制备方式通常是通过HCl+LiF刻蚀液刻蚀，这种方法制备的Ti3C2片层表面会附着有-F官能团，对产物性能有所影响，最近有研究者通过NaOH铝热反应的方法成功制备无-F Ti3C2Tx并探究其在电化学方向上的应用。目前对MXene的研究主要为对以Ti3AlC2为原材料制备得到的Ti3C2Tx片层的研究，对与其结构类似片层替换的Ti3CNTx这种MXene的研究较少。本文以Ti3AlC2和Ti3AlCN两种MAX相为原材料，分别采用酸刻蚀与碱刻蚀的方式成功制备得到了相应MXene Ti3C2与Ti3CN，对制备材料进行表征，并对制备材料在酸性电解液与碱性电解液中的电化学性能进行测试。对材料电化学测试结果进行分析，得到其性能对比。实验结果表明除了酸刻蚀MXene片层在碱性电解液中的测量，两种制备方式得到的Ti3C2Tx片层都具有高于Ti3CNTx的电化学性能，其中碱刻蚀得到的Ti3C2Tx在酸性电解液（1 M H2SO4溶液）比电容最高，可以高达374.6 F/g，性能远高于市面上应用的碳材料。对电化学性能测试的性能异常组进行理论计算，从官能团、离子吸附能与吸附位点、扩散能等方面探讨分析在碱性电解液中酸刻蚀制备的Ti3CNTx的电化学性能高于Ti3C2Tx的原因。即分析MXene中N片层的存在对其充放电过程产生的影响。计算结果表明，-O官能团的存在可以使片层电子容纳能力增加。随着片层内N含量的增加，片层越易与-O端基结合，含-O端基越多，电解液离子越易吸附，材料充放电效率越高。

Two-dimensional MXene is a new kind of two-dimensional material prepared by etching MAX phase raw materials. Since it was synthesized, it has attracted the attention of many researchers. Ti3C2 and Ti3CN are two typical MXenes, which have two-dimensional lamellar structure similar to graphene. The lamellar thickness of MXenes is only a few atoms thick and has the advantages of good stability, high specific surface area and high carrier mobility. Ti3C2 and Ti3CN are considered as alternatives to carbon two-dimensional materials and can be used as electrode materials for supercapacitors. Supercapacitors have wide application prospects in the field of new energy with advantages of high energy density, long cycle life, safety and pollution-free. At present, Ti3C2 MXene is usually prepared by etching with HCl+LiF etching solution. The Ti3C2 layer surface prepared by this method will adhere to - F functional group, which has an impact on the product performance. Recently, some researchers have successfully prepared Ti3C2Tx without -F by NaOH aluminothermic reaction and explored its application in electrochemical direction. At present, the research on MXene is mainly focused on the Ti3C2Tx sheet prepared from Ti3AlC2, but the research on Ti3CNTx sheet substituted by Ti3CNTx sheet with similar structure is less.In this paper, two kinds of MAX phases Ti3AlC2 and Ti3AlCN were used as raw materials. The corresponding MXene Ti3C2 and Ti3CN were successfully prepared by acid etching and alkali etching respectively. The electrochemical properties of MXenes prepared were characterized in acidic electrolyte and alkaline electrolyte. The electrochemical test results of the materials were analyzed and compared. The experimental results show that except for the measurement of acid etched MXene in alkaline electrolyte, the electrochemical properties of Ti3C2Tx obtained by both methods are higher than those of Ti3CNTx. Among them, the specific capacitance of Ti3C2Tx obtained by alkali etching in acidic electrolyte (1M H2SO4 solution) is the highest, which can reach 374.6 F/g, which is much higher than that of carbon materials used in the market. The reason why the electrochemical performance of Ti3CNTx prepared by acid etching in alkaline electrolyte is higher than that of Ti3C2Tx is discussed and analyzed in terms of functional groups, ion adsorption energy, adsorption sites and diffusion energy. That is to say, the influence of N layer in MXene on its charging and discharging process is analyzed. The calculation results show that the existence of -O functional group can increase the electron acceptance capacity of the lamella. With the increase of N content in the lamella, the more easily the lamella binds to the -O terminal group, the more the -O terminal group is, the easier the electrolyte ions are to adsorb, and the higher the charging and discharging efficiency of the material is.

MXene材料 二维材料 超级电容器 电化学性能 第一性原理计算

Mxene two-dimensional material supercapacitor electrochemical properties first-principles calculation

中文

联合培养

南方科技大学

甄莉. Ti3C2和Ti3CN MXenes的制备、表征及其超级电容特性研究[D]. 深圳. 哈尔滨工业大学,2019.