MAX相粉体选择性腐蚀的界面反应机制及过程调控研究

MXenes produced by selective etching of the A element from the MAX phases, are expected to be good candidates for the energy storage applications such as lithium ion batteries, electrochemical capacitors. However, long etching time is usually needed and it is also difficult to regulate the whole process. Since selective etching lies on the kinetics of interface reaction and the activity of A element, this project is focusing on the contact interface of MAX powders (Ti2AlN, Ti2AlC) and liquid medium. Firstly, the reaction mechanism was investigated by the electrochemical method combined with phase and structure analysis. Then, the activity of Al layers was improved by solid solution of gallium and indium atoms. The interfacial area was increased by shear force. And ultimately effective regulation of selective etching process was achieved. Based on the research of this project, the detailed reaction process between the MAX powders and corrosion media was clarified. The interfacial reaction kinetics of selective etching was established and the efficient corrosive media were determined. The effect of solid solution on the activity of Al layers was revealed and the regulation principle of shear force during the selective etching process was elucidated. The implementation of this project will be beneficial to the design and selection of new corrosion media, and also will provide the new method to control the selective etching process of other MAX phases.

MXene是基于MAX相A层原子选择性腐蚀制备的新型二维纳米材料，在超级电容器、锂离子电池等领域具有广泛的应用前景。针对目前制备过程中效率低、可控性差等问题，本项目着眼于选择性腐蚀受界面反应动力学和A层原子反应活性控制这一特征，拟以Ti2AlN和Ti2AlC粉体为腐蚀对象，采用电化学方法并结合物相、结构分析，首先研究两种粉体与腐蚀介质在其接触界面的反应机制，再通过Ga、In原子固溶、机械剪切等手段，提高Al层原子反应活性，增加接触界面，最终实现对选择性腐蚀过程的有效调控。系统研究腐蚀介质中不同离子与两种粉体中Ti层原子和Al层原子的作用机制，搞清Al层原子发生选择性腐蚀的介质类型和界面反应动力学特征，阐明Ga、In原子固溶对Al层原子反应活性的影响机制，揭示机械剪切对选择性腐蚀过程的调控原理。为新型腐蚀介质的设计与选择提供理论依据，并为其它MAX相选择性腐蚀过程的调控提供新的思路和方法。

该项目以MAX相粉体在选择性刻蚀过程中的界面反应机制这一关键科学问题为核心，采用电化学腐蚀的分析思路，并结合了A位固溶活化和机械剪切等手段，对刻蚀过程进行调控。首先利用热爆反应和放电等离子体烧结法制备出了单相和Ga，In原子A位固溶的Ti2AlC和Ti2AlN陶瓷粉体，系统研究了两种粉体在不同刻蚀介质中的物质传输、电荷转移和钝化等过程，探讨了不同介质中各离子与两种粉体中Ti层原子和Al层原子的作用机制，研究了腐蚀介质浓度、温度等对界面反应过程的影响规律，分析了选择性腐蚀的动力学特征和控制因素。同时，研究了Ga，In原子A位固溶以及机械剪切对刻蚀过程的影响机制，进而实现了Ti2AlC粉体的快速高效刻蚀。此外，利用碱性水热处理对两种粉体进行了液相刻蚀，制备出了不同形貌的钛酸盐，并对其电化学性能进行了研究，结果表明该材料具有良好的锂离子存储性能。本研究为新型刻蚀介质的设计与选择提供理论依据，也为其它MAX相粉体刻蚀过程的调控提供了新的思路。