Research Area
Overview of research
Our aim is to drive technological advancements towards a sustainable future, leveraging our extensive material knowledge. Nanosheet materials have unique electrical, chemical, and physical properties based on their crystal structure and constituent elements. 2D materials with high surface area and porous structure are considered ideal for applications such as separation processes, catalysts, adsorbents, membranes, etc. Unlike 3-dimensional functional particles, 2D materials can be easily formed into ultra-thin films due to their flat structure. We are exploring new synthesis methods, mass production techniques, and characterizing 2D materials, with the goal of developing new applications, especially in energy-environment related devices.
Chemistry for new 2D materials
Graphene can be produced in large scale through mechanical exfoliation of natural flakes, but lacks pores in its basal plane, limiting its ability to separate ions and gases. Porous structures with atomic pores are ideal for creating high-performance gas and RO membranes. However, typical porous materials such as MOFs and zeolites have isotropic particle shapes and are difficult to use in practical membrane applications and thin film fabrication. Converting these 3D structures into nanosheet form is crucial for producing high-performance functional thin films. Although there are over 50,000 MOFs and 200 zeolites, only a few nanosheet structures have been reported. Our goal is to develop a new synthesis method to convert these abundant 3D materials into 2D shapes, and to control key material characteristics such as aspect-ratio, pore-size, thickness, crystal structure, and surface functionality. Most importantly, the new materials must be produced in bulk scale for practical and industrial use.
Hybrid nanomaterials
Microporous materials like zeolites, MOFs, and activated carbon are commonly used for catalytic and separation purposes. In industrial applications, these materials must be transformed into hierarchically porous structures that have high mass transfer, low pressure drop, effective heat management, and strong mechanical and chemical stability. Our focus is on developing hybrid materials using 2D materials and microporous materials, and to apply them in large scale body processing. The aim is to utilize these materials in various applications such as catalysis, adsorbents, oil/water selective filters, and batteries.
Extremely thin membrane for separation
The separation process has been explored in various fields with different separation objectives. Distillation, chemical absorption, and physical adsorption are commercially available techniques. However, membrane separation is being adopted globally due to its economical benefits of improved energy efficiency and low installation cost. To develop a better membrane, it's essential to produce a defect-free thin film with a nanometer-level thickness and the ability to produce atomic pores of a specific size. Our group uses stacked 2D materials to create an ultra-thin selective layer on a porous support for gas separation, nanofiltration, and desalination. The thinness of the selective layer leads to dramatically improved permeation of molecules, surpassing previous polymer-based membranes. Currently, we focus on carbon-based membranes for reverse osmosis, nanofiltration, and battery separators, while exploring new 2D material structures for gas separation.
2D material/polymer composite for gas separation
The primary benefit of porous nanosheets is their ultra-thin thickness compared to traditional porous materials like zeolites and MOFs. The high aspect ratio makes it possible to create thin films with a nanometer-scale thickness. Porous nanosheets have the potential to create high-performance membranes through combining with polymers or 2D materials like graphene. The addition of a sheet with an aspect ratio of 1000 to a polymer at a concentration of 10% or higher is believed to result in a high-performance membrane comparable to a continuous crystal membrane.
2D materials for ion recovery
The demand for Li-ion batteries (LIB) is growing due to the increase in eco-friendly vehicles, leading to an increase in spent batteries. LIBs contain toxic substances that can cause environmental pollution if not properly disposed. To address this, recovery of these ions is being explored as a new resource, but traditional recovery methods are expensive. Our group is focused on developing 2D material-based membranes with high ion selectivity to reduce energy demand and make recovery more efficient. This will be achieved through modification of channel size and functional groups.
Carbon nanotubes for Li batteries and energy applications
Enhancing the energy density and performance of Li batteries is critical for accelerating the adoption of energy storage devices in our life. One promising avenue involves integrating Carbon Nanotubes (CNTs) as conductive elements within cathode and anode materials to reduce the volume of electrodes and enhance the ability of fast charge/discharge. Given their remarkable electrical properties, mechanical robustness, and chemical durability, CNTs offer the potential to replace conventional conductive materials in cathodes, leading to a 30% reduction in material usage. Furthermore, CNTs can address the issue of volume expansion of silicon-based anode materials. We focus on advancing the quality of these CNTs and dispersions. Our approach involves precise control over their structure, composition, and functionalization. By analyzing their dispersion morphology through rheological assessments, we aim to fine-tune their characteristics and create impeccable conductive materials for energy devices and electronics.
Fuel cell/Ion-exchange membranes/Electro-catalysis
PEMFCs convert chemical energy from hydrogen into electricity using a proton exchange membrane as an electrolyte. They have potential for clean and efficient power generation and improvement of performance and cost is a key goal in the multidisciplinary field of PEMFC research. The main components of PEMFCs are the anode, cathode, and proton exchange membrane, with a focus on improving the performance of the electrodes and developing a more durable and cost-effective proton exchange membrane. Our group has expertise in both 2D materials and PEMFCs research and is exploring the potential of using 2D materials to improve the performance and durability of PEMFCs. We invite you to visit our 2D materials lab to discuss collaboration opportunities in PEMFC research and work together to advance the technology and make it a more competitive alternative to other energy sources.
Multi-functional nanocoating
for energy and environmental applications
2D materials with structure control have various potential applications in the thin film industry, beyond just membrane technology. Their properties, including electrical conductivity, mechanical strength, light absorption, and thermal conductivity, can be customized by adjusting their atomic structure and composition. Carbon-based structured 2D materials, for instance, have high conductivity and can be utilized as energy storage electrodes in batteries and supercapacitors. They can also be used to produce high-value added thin films such as electromagnetic wave shields and heat-conducting films. On the other hand, semiconductor and inorganic porous 2D materials with insulating properties are suitable for applications like photo-reactive membrane reactors, low-k thin films, and drug delivery.