Surface Modifications of InSe and MXene Two-Dimensional (2D) Materials and their Impact on the Chemical Stability and Interactions with Bacterial Models Relevant to the Environment

Abstract

Nanosheets are layered two-dimensional nanostructures with thickness in the nano-range, but with properties completely different from the bulk precursors or 3D nanomaterials. Layered materials are defined as solids with strong in-plane chemical bonds, but weak out-of-plane van der Waals interactions. Their unique structural properties enable new functional properties that are important for a multitude of applications. The goal of my research project is to investigate the impact of surface chemistry modifications of 2D materials like InSe and MXenes on their stability and interactions with environmentally relevant bacterial organisms. From a basic science perspective, this study increases the molecular level understanding of the interactions between hydrophobic 2D materials like InSe and amphiphilic adsorbates. The primary choice of our 2D material is InSe, which is an emerging semiconductor 2D material having a direct band gap, already used in broadly distributed nanotechnologies. Usage of InSe and similar 2D materials is expected to grow exponentially in the next decade. However, their unique morphology and ability to produce reactive oxygen species (ROS) could adversely affect human health and the environment. There is an urgent need to address these environmental concerns before the expected exponential growth of their use. Aim 1 of the project is to perform surface modifications on originally hydrophobic InSe nanosheets by physisorption of an amphiphilic molecule and a natural organic matter (NOM) simulant to make them water soluble and understand the impact of this modification on the chemical stability of the nanosheets. Physisorption of NOM components on InSe nanosheets is likely to naturally happen in the environment (natural water) when InSe nanosheets are disposed at the end of devices lifetime, and thus they act as model environmental aqueous solutions. Aim 2 is to investigate the impact of the surface-modified InSe 2D materials soluble in aqueous media on Shewanella oneidensis MR-1, which is an environmentally relevant Gram-negative bacterial cell model. Aim 3 is to investigate the environmental impact of a different highly conducting and water-soluble emerging set of 2D material, MXenes, in unmodified and surface-modified forms with different functional groups as well as fabricated on thermoelectric composite materials, on Shewanella oneidensis MR-1.