University of Nebraska-Lincoln
514A Hamilton Hall
Lincoln, NE 68588-0304
The Cheung group’s research focuses on investigating the fundamentals underlying the structure-function activity relationships of nanostructured materials for energy and biological applications. As bulk materials shrink in size to the nanoscale, more and more of their total mass are part of their surfaces. Thus, the atomic structures of the surface become dominant in dictating the overall chemical and physical properties of the materials. Understanding of such intricate relationships at the atomic level can provide invaluable knowledge to engineer materials with designed functions.
We approach our research questions by:
(1) Developing synthetic methods to produce inorganic and inorganic-organic hybrid materials with controlled shape, size, atomic lattice, and atomic defects;
(2) Conducting properties measurements to discover the structure-function activity relationships of nanomaterials;
(3) Evaluating the efficacy of nanomaterials with functional designs for target tailored applications.
Our group has developed multipronged expertise in the syntheses and structural characterizations of transition metal borides and chalcogenides, especially in the areas of lanthanides. Synthetic methodologies developed by our group include hydrothermal and solvothermal synthesis, microwave synthesis, chemical vapor deposition, ozone-mediated synthesis, sol-gel synthesis, plasma synthesis, chemical bath synthesis, and ion beam-assisted deposition. Electron microscopy, X-ray diffraction, and X-ray absorption spectroscopy are key techniques used in the structural and lattice characterizations of these designed materials. Applications of these developed materials explored by our group include chemical catalysis, photovoltaics, therapeutics, biofouling coating, and radiation sensing.
One major research theme in Cheung group is Nanoceria Chemistry. Cerium oxide (CeO2 or ceria) is a technologically important transition metal oxide in modern societies. Its numerous applications range from semiconductor processing, catalysis, to biomedical therapeutics. Our group has achieved controlled syntheses of a variety of different nanostructured ceria (or nanoceria) with defined facets (“surface lattice) and defect chemistry. These engineered catalysts have been applied for numerous reactions. Examples of these reactions include carbon monoxide oxidation, carbon-carbon bond formation, electrochemical oxidation of alcohols, conversion of carbon dioxide to dialkyl carbonates, and generation of reactive oxygen species. (Figure 1).
Our group continues to develop new synthetic methods to create nanosized lanthanide oxides. One recent example is the ozone-mediated method to produce nanoceria particles with high concentrations of atomic defects. These defects partially cause the usually yellowish-to-white ceria to appear “fiery red”. (Figure 2). The materials and their variations are being investigated for enzyme-mimic reactions.
1. “Structure–activity relationship of nanostructured ceria for the catalytic generation of hydroxyl radicals” T.J. Fisher, Y. Zhou, T.-S. Wu, M. Wang, Y.-L. Soo, and C.L. Cheung. Nanoscale, 11, 4552-4561 (2019). DOI: 10.1039/c8nr09393h
2. “Ozone-mediated synthesis of ceria nanoparticles” A. Bhalkikar, T.-S. Wu, C.M. Marin, T.J. Fisher, M. Wang, I.H. Wells, A. Sarella, Y.-L. Soo, and C.L. Cheung. Nanoscale 10, 9822-9829 (2018). DOI: 10.1039/c8nr01971a
3. "Kinetic and mechanistic investigations of the direct synthesis of dimethyl carbonate from carbon dioxide over ceria nanorod catalysts", C.M. Marin, L. Li, A. Bhalkikar, J.E. Doyle, X.C. Zeng, and C.L. Cheung. J. Catal. 340, 295-301 (2016). DOI:10.1016/j.jcat.2016.06.003
4. "One-pot conversion of cellobiose to mannose using a hybrid phosphotungstic acid-cerium oxide catalyst", Z.C. Gernhart, A. Bhalkikar, J.J. Burke, K.O. Sonnenfeld, C.M. Marin, R. Zbasnik, and C.L. Cheung. RSC Adv. 5, 28478-28486 (2015). DOI: 10.1039/c5ra02645h
5. "Crystalline α-Sm2S3 nanowires: Structure and optical properties of an unusual intrinsically degenerate semiconductor", C.M. Marin, L. Wang, J.R. Brewer, W.N. Mei, and C.L. Cheung. J. Alloy. Compd. 563, 293-299 (2013). DOI: 10.1016/j.jallcom.2013.02.082