Inherently Porous Atomically Thin Membranes for Gas Separation

Membranes made from atomically thin materials promise hundreds of times higher production rates than conventional polymer membranes for separation applications. Graphene is impermeable to gases but becomes selectively permeable once pores are introduced into it but creating trillions of nanopores over large areas is difficult. By instead choosing an inherently porous two-dimensional material with naturally identical pores repeated at high density, we may circumvent this challenge. In this work, we explore the potential of two candidate materials, 2D polyphenylene and graphdiyne. We synthesize cyclohexane-m-phenylene, a monomer of 2D polyphenylene. We then develop an atomic force microscopy technique for measuring the permeance of nanoscopic areas of materials and perform the first gas permeance measurements of graphdiyne and demonstrate molecular sieving. Efforts to scale-up employ continuum transport equations for simple modeling so we develop analytical approximations for the rate of mass transfer rate by advection-diffusion in creeping flow through an orifice plate

Atomistic Modeling of Solid Interfaces in All-solid-state Li-ion Batteries

All-solid-state Li-ion battery based on solid electrolyte is a promising next-generation battery technology, providing intrinsic safety and higher energy density. Despite the development of solid electrolyte materials with high ionic conductivity, the high interfacial resistance and interfacial degradation at the solid electrolyte–electrode interfaces limit the electrochemical performance of the all-solid-state batteries. Fundamental understanding about the solid-solid interfaces is essential to improve the performance of all-solid-state batteries. In this dissertation, I perform first principles computation to bring new understanding about these solid interfaces. Using our developed computation approach based on large materials database, I calculated the intrinsic electrochemical stability window of solid electrolytes and predicted interphase decomposition products. I revealed the effects of different types of interphase layers on the interface stability and battery performance, and also provided interfacial engineering strategies to improve interface compatibility. Lithium metal anode can provide significantly higher energy density of Li-ion batteries. However, only a limited number of materials are known to be stable against lithium metal due to its strong reducing nature. Using first-principles calculations and large materials database, I revealed the general trend of lithium reduction behavior in different material chemistry. Different from oxides, sulfides, and halides, nitride anion chemistry exhibits unique stability against lithium metal, which is either thermodynamically intrinsic or a result of stable passivation. Therefore, many nitrides materials are promising candidate materials for lithium metal anode protection. Since solid electrolytes in all-solid-state batteries are often polycrystalline, the grain boundaries can have an important impact on the ion diffusion in solid electrolytes. I performed molecular dynamics simulations to study the ion diffusion at grain boundaries in solid electrolyte materials, and showed the distinct diffusion behavior at grain boundaries different from the facile ion transport in the bulk. In addition, I studied the order-disorder transition induced by mechanical strain in lithium garnet. Such transition can lead to orders of magnitude change in ionic diffusivity. This series of work demonstrated that computational modeling techniques can help to gain critical fundamental understandings of the solid interfaces in all-solid-state Li-ion battery, and to provide practical engineering strategies to improve the battery performance

Towards a circular economy: fabrication and characterization of biodegradable plates from sugarcane waste

Bagasse pulp is a promising material to produce biodegradable plates. Bagasse is the fibrous residue that remains after sugarcane stalks are crushed to extract their juice. It is a renewable resource and is widely available in many countries, making it an attractive alternative to traditional plastic plates. Recent research has shown that biodegradable plates made from Bagasse pulp have several advantages over traditional plastic plates. For example, they are more environmentally friendly because they are made from renewable resources and can be composted after use. Additionally, they are safer for human health because they do not contain harmful chemicals that can leach into food. The production process for Bagasse pulp plates is also relatively simple and cost-effective. Bagasse is first collected and then processed to remove impurities and extract the pulp. The pulp is then molded into the desired shape and dried to form a sturdy plate. Overall, biodegradable plates made from Bagasse pulp are a promising alternative to traditional plastic plates. They are environmentally friendly, safe for human health, and cost-effective to produce. As such, they have the potential to play an important role in reducing plastic waste and promoting sustainable practices. Over the years, the world was not paying strict attention to the impact of rapid growth in plastic use. As a result, uncontrollable volumes of plastic garbage have been released into the environment. Half of all plastic garbage generated worldwide is made up of packaging materials. The purpose of this article is to offer an alternative by creating bioplastic goods that can be produced in various shapes and sizes across various sectors, including food packaging, single-use tableware, and crafts. Products made from bagasse help address the issue of plastic pollution. To find the optimum option for creating bagasse-based biodegradable dinnerware in Egypt and throughout the world, researchers tested various scenarios. The findings show that bagasse pulp may replace plastics in biodegradable packaging. As a result of this value-added utilization of natural fibers, less waste and less of it ends up in landfills. The practical significance of this study is to help advance low-carbon economic solutions and to produce secure bioplastic materials that can replace Styrofoam in tableware and food packaging production