SYNTHESIS AND CHARACTERIZATION OF FUNCTIONAL NANOMATERIALS
We are developing advanced nanomaterials using organic or aqueous solution synthesis. Our aim is to control the size, shape, composition and heterostructures of these materials, by tuning the reaction conditions to tailor crystal nucleation and growth at the nanoscale. Enabled by these new materials, we are seeking for functional applications in catalysis, energy storage and conversion, and many other fields, with particular interests in the following directions.
ELECTROCATALYSIS FOR ENERGY STORAGE AND CONVERSION
Within the last two decades CO2 sequestration and conversion has gained interest and is now essential in solving the global climate crisis. To date there have been several techniques for conversion of CO2 to commercial products, but CO2 electroreduction has become the most popular among them. Electrochemical reduction of CO2, an artificial way of carbon recycling, represents one promising solution for energy and environmental sustainability because of its ability to be driven by intermittent forms of energy (solar and wind), use of innocuous electrolytes and catalysts and its fuel cell having a compact and modular design. However, it is plagued with sluggish kinetics and high electrode potentials to generate high valued products. Additionally, more economical catalysts, like copper, lack selectivity for desired products. Our lab seeks to explore various catalytic systems that overcome these deficiencies and advances fundamental understanding in catalyst design and mechanism towards CO2 reduction.
We are developing a series of precious metal based catalyst by wet chemical synthesis for the cathode of fuel cell. Our aim is to find the champion structure and composition for ORR reaction, that is, high activity and high stability as well. We are now developing a new Co@Pt core-shell catalyst for ORR reaction, which shows 10 times higher activity than state-of-the-art Pt/C catalyst and the record stability (only 13% loss of mass activity after 30,000 cycles).
We are looking for a sustainable and environmental friendly catalyst with high activity and long term stability for the cathode of metal-air batteries. By controlling the structure and composition, we are going to identifying the best catalyst for both ORR and OER, such as Pt-CoOx and Pd-NiFeOx hetero-structure catalyst.
HETEROGENEOUS CATALYSIS FOR SUSTAINABILITY
Nitric oxide is the main pollutant from vehicle emissions. Mechanistic understanding of direct NO decomposition is of vital importance in design of high-performance catalyst. Zeolites containing transition metal ions have been investigated extensively for direct NO decomposition. Comparative studies on different catalysts (supported noble metal catalysts, composite metal oxide, zeolitic type catalysts, etc.) have been performed, and transition-exchanged zeolites showed good activity.
This project is aimed to study the adsorption compression phenomenon on transition-exchanged zeolites for ways to enhance the reaction rate for commercially relevant reactions and ultimately a guideline for future catalyst design. Various zeolite supports, including MFI, BEA, FAU, CHA, are used in this project and a combined experimental (kinetic and spectroscopic study) and theoretical (DFT) investigation on the catalysis are dedicated to reveal the active sites-performance relationship in terms of catalytic activity. The investigation of adsorption compression in this project will guide the future development of NOx abatement catalyst as well as provide in-depth understanding in NOx chemistry over zeolitic catalysts.
Our research team aims to advance the field of heterogeneous catalysis by solving our society’s toughest sustainability challenges. Among these problems is the production and separation of nitrogen and phosphorus. These elements are essential for life and are the primary ingredients in the industrial fertilizers that have enabled the rapid spread of modern agriculture. With impending shortages of mined phosphorus rocks in the next few decades and the high energy costs associated with ammonia synthesis, it is necessary to develop new technologies to sustainably extract nitrogen and phosphorus from renewable sources.
We have developed advanced cerium oxide nanocatalysts to dephosphorylate water-based biomass feedstocks at ambient reaction conditions, producing useful chemical byproducts and inorganic phosphate with minimal energy costs. Systematic kinetic studies on nanocatalysts with varying crystal facets, surface defects, and morphologies were conducted to elucidate mechanisms and to improve activity and recyclability. We also explore novel zeolite absorbents for the sequestration of dissolved nitrogen and phosphorus from wastewater and the effluents of digested algal biomass. Combining these efforts, we have developed unique and industrially-practical methods to extract and isolate these important nutrients from biological feedstocks.
ADVANCED MAGNETIC NANOMATERIALS
Research focus involves the synthesis, characterization and analysis of magnetic nanoparticles for various applications including electromagnetic wave absorption (radar absorption), antibody conjugation and virus capture. Various soft (i.e. Fe3O4) and hard phase (i.e. Co, SmCo5 or Nd2Fe14B) magnetic nanomaterials are synthesized via organic solution synthesis. Preliminary materials are characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX) or inductively coupled plasma mass spectrometry (ICP-MS). Thorough magnetic analysis of materials is conducted on a vibrating-sample magnetometer (VSM) or superconducting quantum interference device (SQUID). Electromagnetic measurements are taken using a vector network analyzer (VNA).