Tailored surface modification of 2D materials for functional devices

Abstract

2 dimensional (2D) materials have unique properties including strong mechanical strength, flexibility, large surface area compared to bulk counterpart. Among 2D materials, 2D transition metal carbides/nitrides MXenes have drawn big research interests owing to their extraordinary electrical properties, and hydrophillicity utilized in energy storage, and electromagnetic interference (EMI) shielding. However, pristine 2D materials are hard to meet specific demands for different applications. Physical properties including surface energy, electronic energy level, surface reactivity need to be tuned via surface modifications. In this dissertation, interlayer adhesion, and surface functionalization are introduced to 2D materials to develop surface modified 2D materials for functional devices. Initially, mussel-inspired nanoadhesives are applied to 2D MXenes to yield oxidant-resistant, highly aligned MXene film as an EMI shielding materials. The nanoadhesives can also attach MXene to 3D substrate to develop stable pressure sensor with dual-mode acquisition of pressure, and strain, enabled by strong EMI shielding properties of MXenes. Secondly, a covalent-noncovalent two-step functionalization is applied to 2D materials. This functionalization enables an heterostacked structure of electronically distinct two 2D materials, MXene and graphene oxide, for EMI shields with promoted internal scattering. Furthermore, a hierarchically porous MXene structure can be achieved through similar functionalization strategy which could suppress ‘shuttling effect’ of polysulfide in lithium sulfur battery.