基于双连续凝胶的Mxene三维多孔导电支架的构筑、稳定机理及结构调控

3D porous conductive scaffolds have been playing an increasingly important role in energy storage devices. Template-assisted methods have generated a great deal of interests due to their ability to produce well-defined 3D structures. Soft templates can be easily removed and therefore are important for mass production of the scaffolds. Bicontinuous interfacially jammed emulsion gel (Bijel) is a unique Pickering emulsion with two inter-penetrating continuous fluid domains sharing an interface jammed with neutrally wetting colloidal particles (contact angle is close to 90o). It makes bijel an ideal template for template-assisted methods. Interfacial assembly of colloidal particles into 3D network is a simple route for making the scaffolds. However, conductive particles in general have inactive surface chemistry, such as graphene, it is difficult for them to become neutrally wetting colloidal particles with critical requirement for surface chemistry. It is possible to use strong oxidation for introduction of functional groups, but which makes them lose the conductivity. It remains the challenge for bijels to be arrested by conductive particles. Newly discovered Mxene is an ideal particle for solving this problem as it has been reported to have high conductivity and also active surface chemistry. In order to realize a new route for gaining conductive scaffolds, this project is to explore the approaches for tuning surface chemistry of Mxene, optimize the production of Mxene-based bijels and understand stability mechanism of self-assembled Mxene-based 3D network during the removal of bijel templates.

三维多孔导电支架在储能器件中的作用日益突出。模板法可以制备结构规整的支架因而受到了普遍关注，其中由液体形成的软模板具有易脱除的优点，对模板法的大规模应用有重要意义。双连续凝胶是一种特殊的Pickering 乳液，它具有两个独立并且互相穿插的连续液体相，因中性湿润（接触角90度）胶体堵塞界面而发生结构捕获，是理想的软模板。胶体通过界面组装成三维网络是构筑导电支架的一种简便途径。但是导电胶体表面化学性质不活泼，如石墨烯，难形成对表面化学性质要求苛刻的中性湿润胶体，通过氧化法又会使其失去导电性，所以引入导电胶体一直是双连续凝胶中没有解决的难题。最新发现的二维材料Mxene兼有高导电性与活泼的表面化学性质，是帮助解开这一难题的理想胶体。本项目将探索Mxene表面化学的调控方法，优化Mxene-双连续凝胶的制备工艺，探究Mxene 三维网络去模板过程中的稳定机理，为制备三维多孔导电支架提供新的方法。

MXene是一种新型过渡金属碳或氮化物二维晶体材料，集金属导电性与高表面活性于一身，在二维材料家族中独树一帜。这个奇特的性质使得MXene已经在能源存储，吸附，传感器，电磁屏蔽等领域展现出巨大的应用前景。如何将MXene单元组装成三维多孔结构是实现上述应用的重要科学问题之一。本项目主要围绕MXene表面功能化，发展了MXene单元相互作用以及表面亲水／亲油平衡的调控方法，实现了MXene单元在单一水相以及水／油界面的自组装成三维网络，由此捕获了水凝胶和高内相皮克林乳液两种热力学非平衡的软物质形态，并通过脱除液体后获得了稳定三维多孔材料。基于MXene的多孔材料在电磁屏蔽与储能器件中展示了巨大的潜在用途。除此之外，本项目还探索了制备双连续凝胶的新方法以及MXene纳米复合材料的制备方法。MXene不仅可以大幅度提升基体材料的力学性能，同时可以强化基体材材料的功能性比如导质子率与抗紫外线的能力。