【作者】 张倩；

【导师】 许群； 崔鑫炜；

【作者基本信息】 郑州大学 ， 材料与化工（专业学位）， 2023， 硕士

【摘要】 近年来,全球对能源与水的需求越来越大,生产几乎所有类型的传统能源的生产、转化和利用都需要水,而大部分淡水资源的净化也需要能源驱动。因此,如何采取有效策略,处理水与能源之间相辅相成又相互制约的关系,是当今世界发展所面临的最重要的挑战之一。碳基材料的微纳结构调控,可以从微观尺度对分子、离子、电子的传输行为进行有效控制,对于海水淡化与能源存储中材料技术的可持续性发展至关重要。然而,随着应用领域对性能的要求不断提升,碳基材料微纳结构的调控尺度需要精确到埃米（?）级别。更为重要的是,在埃米级别精度上的微纳结构调控对分子、离子、电子传输的影响机制尚未明晰,亟待深入研究。基于此,本论文针对海水淡化盐水分离以及锂离子电池硅氧负极材料中的关键问题,从碳纳米材料出发,通过设计其微纳结构精细调控新策略,分别构筑了亚纳米石墨烯基二维限域孔道的纳滤膜材料以及三维碳基导电网络结构,实现了优异的综合性能。主要内容如下:（1）石墨烯基二维纳米限域的原位构筑及其反常离子渗透现象的机理研究针对由氧化石墨烯（GO）等亲水二维材料组装而成的纳滤膜不能同时实现高水通量以及高离子拒绝率的瓶颈问题,本章首先使用了一种金属有机材料（Ni-pPD）,通过构建其与还原氧化石墨烯（rGO）的二维异质结构,在由Ni-pPD@rGO异质结堆叠的滤膜中,形成了0.6 nm且接触角为84°的石墨烯疏水孔道。在正向离子渗透实验时,我们发现了反常的只针对水分子传输的门控现象。机理研究表明,在亚纳米石墨烯限域条件下,水分子形成了有序的类六边形结构。当两边静水压相同时,此结构可以同时阻碍水与离子的渗透;而当水侧静水压增加至很小的阈值压力(<10^-3bar)时,限域中的有序水以牛顿摆的形式快速传输。此机理使得新型二维材料纳滤膜在室温下同时实现了高水通量(45.4 L m^-2 h^-1)与高离子拒绝率(约10^-4 mol m^-2h^-1)的优异性能。（2）碳基复合导电网络的构建及其在硅氧负极中的应用针对硅氧负极体积在嵌锂过程中体积膨胀导致粉化脱落,而现有三维碳基导电孔道结构设计会牺牲电极材料体密度的问题,本章使用Super P导电炭黑-单壁碳纳米管-晶须纳米碳纤维组成的三维电子、离子快速导电网络,利用网络内的限域空间保护硅氧负极,同时利用晶须纳米碳纤维的刚性及其表面羟基形成的界面氢键连接,构建力学性能优异的多功能网络,通过表界面结构精确控制,纯的碳包亚硅电极可在0.5C和10C下分别达到1753.5 mAh g^-1和622.5 mAh g^-1的高容量,其与90 wt.%的石墨混合制备的硅氧负极可以获得565 mAh g^-1的高容量以及优异的容量循环保持率。更多还原

【Abstract】 In recent years,there has been a growing global demand for energy and water,with almost all forms of conventional energy production,conversion,and utilization requiring water.Furthermore,the purification of the majority of freshwater resources also necessitates energy-driven processes.Effective strategies are needed to deal with the interdependent and mutually restrictive relationship between water and energy,which is one of the most important challenges facing the world’s development today.The micro-nanostructure control of carbon-based materials can effectively control the transport behavior of molecules,ions,and electrons from a microscopic scale,which is crucial for the sustainable development of material technology in seawater desalination and energy storage.However,with the increasing demand for performance in application fields,the modulation of micro-nanostructures in carbon-based materials needs to be accurate to the?ngstrom（?）level.More importantly,the mechanism of the influence of micro-nanostructure control at the?ngstrom level on the transport of molecules,ions,and electrons is not yet clear and requires further research.Based on this,this project has constructed a two-dimensional,sub-nanoconfined,graphene-based nanofiltration membrane and a three-dimensional,carbon-based conductive network structure,in addressing the key issues in seawater desalination as well as in the silicon mono-oxide anode materials for lithium-ion batteries,respectively.The main contents are as follows:（1）Anomalous liquid gating from atomic-scale graphene capillaries for precise and ultrafast molecular sievingAddressing the bottleneck problem of current nanofiltration membranes assembled from hydrophilic two-dimensional materials,such as graphene oxide（GO）,which cannot simultaneously achieve high water flux and high ion rejection rate,this chapter first employed a metal-organic material（Ni-pPD）to construct a two-dimensional heterostructure with reduced graphene oxide（rGO）,forming hydrophobic graphene nanochannels with a size of 0.6 nm and a contact angle of 84°in the stacked membrane of Ni-pPD@rGO heterostructures.During the forward osmosis experiments,we observed an anomalous gating phenomenon that selectively permits water transport.Mechanism studies indicated that under the sub-nanometer confinement of graphene,water molecules formed an ordered quasi-hexagonal structure.When the hydrostatic pressure on both sides is equal,this structure can effectively block both water and ion permeation.However,when the hydrostatic pressure on the water side increases to a small threshold pressure(<10^-3 bar),the ordered water in the confinement can be rapidly transported in a Newtonian pendulum-like fashion.This mechanism enables the new two-dimensional membrane to achieve both high water flux(45.4 L m^-2 h^-1)and high ion rejection rate(approximately 10^-4mol m^-2 h^-1)with superior performance at room temperature.（2）The construction of a three-dimensional（3D）carbon-based conductive network and its application in silicon monoxide anodes.The severe volume expansion of silicon-based anodes during lithium insertion causes pulverization and detachment,while the existing 3D carbon-based conductive channel structures sacrifice the electrode material’s bulk density.To address these issues,we used a 3D conductive network for rapid electron and ion transport,which was composed of Super P conductive carbon black（Super P）,single-walled carbon nanotubes（SWCNTs）,and vapor-grown carbon nanofiber（VGCNF）.This 3D structure protected the silicon monoxide anodes by utilizing the confined space within the network.In addition,the rigidity of VGCNFs and the hydrogen bonds formed across the interface by their surface hydroxyl groups strongly strengthened the structure,forming robust and multifunctional 3D network.As such,pure carbon coated silicite electrode has achieved high capacities of 1753.5 mAh g^-1 at 0.5C and 622.5 mAh g^-1at10C,respectively.In addition,we can achieved a high capacity of 565 mAh g^-1 with excellent capacity retention for the mixed anodes of carbon coated silicite with 90 wt.% of graphite.更多还原