(6bw) Catalytically Active and Hazardous Gas Adsorbent Polymer Fibers Functionalized By Atomic Layer Deposition and Metal-Organic Framework Thin Films

Research
Interests: Metal Organic Framework Thin Film Synthesis and Practical
Application

Noxious compounds,
including toxic industrial chemicals (TICs) (e.g., ammonia, chlorine, hydrogen
sulfide, nitrogen dioxide) and chemical warfare agents (CWAs) (e.g., sarin,
soman, mustard gas) can pose a substantial threat to human health and the
environment. Increased international threats and broader industrial usage is
drawing research attention to practical and effective means for compound decontamination
and isolation. Current technologies for ambient and environmental purification
technology mainly relies on filtration and adsorption via impregnated activated
carbon-based porous materials and metal oxides. However, such active components
possess limited shelf-life, target specificity and overall effectiveness.

Metal-organic frameworks
(MOFs) are a new class of porous materials featuring highly crystalline and
exceptional high surface area¹ Some
MOFs are known to be stable, versatile and rapidly functional for removing and
catalytically decomposing noxious compounds. MOF materials are also well
regarded for applications in gas storage and separation, drug delivery, light
harvesting, electronics and others. In addition, the facile tunability in
functional groups and metal clusters of MOFs allows them to be tailored and
designed adsorb and abate specific target chemicals.² Most
current studies of MOFs focus on synthesized power materials. For most
applications, however, powders lead to practical limitations in application
development.

My interest is in
formation, characterization and evaluation of MOF thin film materials formed on
functional and active surfaces for applications in environmental protection,
personal safety and security, energy and other advanced fields. To overcome current
critical challenges, I started working on a MOF-related project funded through
DoD, primarily focused on integrating various MOFs onto polymeric non-woven
textiles (MOF-functionalized textiles) by capitalizing on atomic layer
deposition (ALD) technique, and investigating their catalytic and adsorbent performance
against a range of CWAs, their simulants, and TICs.

The first research
achievement I made is entitled Catalytic MOF-Cloth Formed via Directed
Supramolecular Assembly of UiO-66-NH₂ Crystals on Atomic Layer
Deposition-Coated Textiles for Rapid Degradation of Chemical Warfare Agent
Simulants.¹
In this work, I came up with a novel approach to assembling as-synthesized
Zr-based UiO-66-NH₂ crystals onto ALD-treated nonwoven polypropylene
(PP) fibrous scaffolds, followed with demonstrating a promising catalytic performance
of the products against a CWA simulant, dimethyl 4-nitrophenyl phosphate (DMNP)
with a half-life of less than 5 minutes. The facile assembly method using
surfactant assembly agents facilitates a swift MOF integration under mild assembly
environment (a few hours at 25 ^oC), otherwise it generally takes
more than 20 hours at higher than 80 ^oC.

The second research
project I completed is UiO-66-NH₂ Metal-Organic Framework
(MOF) Nucleation on TiO₂, ZnO, and Al₂O₃
Atomic Layer Deposition-Treated Polymer Fibers: Role of Metal Oxide on MOF
Growth and Catalytic Hydrolysis of Chemical Warfare Agent Simulants.³
Herein, I explored a conventional solvothermal integration of UiO-66-NH₂
onto different ALD thin films (i.e., Al₂O₃, TiO₂,
or ZnO), and unveiled how the inorganic ALD layer with different compositions influences
the MOF nucleation mechanism and the quality of the surface-bound MOF. The
results are proved by correlating the material properties with catalytic
performance of MOF-functionalized textiles towards degrading DMNP. Through this
work, we found that TiO₂ surface enables to form a robust and more
catalytically active surface-anchored MOF crystals compared to the other
inorganic films tested.

In addition to the
research progress above, I have been controlling the mass loading of UiO-66-NH₂
onto ALD TiO₂ coated PP fibrous mats and investigating catalytic and
permeation properties of MOF-functionalized textiles to provide more pragmatic and
quantifiable insights into protective equipment field.

Finally, I was not only
limited to working on Zr-based MOFs, but also have recently achieved growing a robust
and water-stable porphyrin-based Cu-TCPP MOF onto non-woven textiles, consisting
of a copper paddle-wheel structure of metal clusters interconnected by
porphyrin-based organic linkers. I also controlled the orientation of two-dimensional
structure of the MOF onto fiber substrates by utilizing a modified route of a hydroxy
double salt (HDS) mediated approach and, for the first time, found that the
oriented MOF exhibited a promising removal performance for 2-chloroethyl ethyl
sulfide (CEES), a blistering agent simulant, as well as ammonia even under
humid environment (80% RH). Besides, I successfully fabricated other M-TCPP [M
= Cu, Zn, Co, and Al] functionalized textiles and observed substantially
improved CEES absorption capacity (mol_(CEES)/kg_(adsorbent))
in Al-TCPP MOF in comparison with Cu-TCPP. 

Future Research Interests

My near future research interest
lies in sustainable and clean energy and the environment using multiple
nanomaterials like semiconducting, metallic, and porous structures (including
MOFs) for CO₂ reduction, gas storage/separation, water desalination,
toxic gas removal, water harvesting, and designing advanced membrane devices. In
this regard, I believe that my research experience of thinking out feasible
ideas, material synthesis, characterizing and analyzing the results, and making
a rational conclusion would make me an independent researcher to contribute to sustainable
and clean energy-relevant community.

Teaching Interests:

While I have been being served
as a research- and teaching assistant under MS and PhD programs in the Chemical
Engineering Department, I believe I have developed not only teaching, but also
communicating with students to have them effectively learn both in class and
out of class. Especially such a research and teaching experience makes me
confident of teaching chemical reaction engineering, thermodynamics, and
mathematical approach to solving problems in transport phenomena. In addition,
I can also teach more advanced or elective courses covering, core chemical
engineering topics, for example reaction kinetics, separations, and
thermodynamics, couple together in sample industrial systems. My teaching goal
is to inspire students to actively learn and apply their knowledge to
engineering problems that they are facing and intrigued in, thus fostering the academia
as well as the industry in the end.

Reference

1. Lee, D. T.;
Zhao, J.; Peterson, G. W.; Parsons, G. N., Catalytic ¡°MOF-Cloth¡± Formed via
Directed Supramolecular Assembly of UiO-66-NH2 Crystals on Atomic Layer
Deposition-Coated Textiles for Rapid Degradation of Chemical Warfare Agent
Simulants. Chem. Mater. 2017, 29 (11), 4894-4903.

2. Zhao, J.; Lee,
D. T.; Yaga, R. W.; Hall, M. G.; Barton, H. F.; Woodward, I. R.; Oldham, C. J.;
Walls, H. J.; Peterson, G. W.; Parsons, G. N., Ultra-Fast Degradation of
Chemical Warfare Agents Using MOF-Nanofiber Kebabs. Angew. Chem. Int. Ed. 2016,
55 (42), 13224-13228.

3. Lee, D. T.;
Zhao, J.; Oldham, C. J.; Peterson, G. W.; Parsons, G. N., UiO-66-NH2 MOF
Nucleation on TiO2, ZnO, and Al2O3 ALD-treated Polymer Fibers: Role of Metal
Oxide on MOF Growth and Catalytic Hydrolysis of Chemical Warfare Agent
Simulants. ACS Applied Materials & Interfaces 2017.