NIU Department of
Chemistry & Biochemistry Where the study of matter...matters!
Assistant Professor
Office: Faraday West 412
Phone: (815) 753-6357
txu@niu.edu
Ph.D., University of Alabama, 2003
B.S., East China University of Science and Technology, 1995
Postdoctoral Research Associate, Argonne National Laboratory, 2004-2006
Research Associate, Texas A&M University, 2003-2004
Inorganic-organic hybrid interfaces and nanomaterials for applications in sensors, energy storage and converstion, solid-state lighting, and molecular electronics.
Direct mass determination of hydrogen uptake using a quartz crystal microbalance. Kulchytskyy, I.; Kocanda, M. G.; Xu, T. (2007) Appl. Phys. Lett., 91: 113507.
Origin of the matching effect in a superconducting film with a hole array. Patel, U.; Xiao, Z. L.; Hua, J.; Xu, T.; Rosenmann, D.; Novosad, V.; Pearson, J.; Welp, U.; Kwok, W. K.; Crabtree, G. W. (2007) Physics Review B, 76: 020508.
Self-assembled monolayer-enhanced hydrogen sensing with ultrathin palladium films. Xu, T.; Zach, M. P.; Xiao, Z. L.; Rosenmann, D.; Welp, U.; Kwok, W. K.; Crabtree, G. W. (2005) Appl. Phys. Lett., 86: 203104.
A spectroscopic study of hexadecylquinolinium tricyanoquinodimethanide as a monolayer and in bulk. Xu, T.; Szulczewski, G. J.; Morris, T.; Amaresh, R.; Gao, Y.; Street, S. C.; Kispert, L.; Metzger, R. M. (2002) J. Phys. Chem. B, 106: 10374-10381.
Periodic holes with 10 nm diameter produced by grazing Ar+ milling of the barrier layer in hexagonally ordered nanoporous alumina. Xu, T.; Zangari, G.; Metzger, R. M. (2002) Nano Lett., 2: 37-41.
Nanoditches fabricated using a carbon nanotube as a contact mask. Xu, T.; Metzger, R. M. (2002) Nano Lett., 2: 1061-1065.
Rectification by a monolayer of hexadecylquinolinium tricyanoquinodimethanide between gold electrodes. Xu, T.; Peterson, I. R.; Lakshmikantham, M. V.; Metzger, R. M. (2001) Angew. Chem. Int. Ed., 40: 1749-1752.
Electrical rectification by a monolayer of hexadecylquinolinium tricyanoquinodimethanide measured between macroscopic gold electrodes. Metzger, R. M.; Xu, T.; Peterson, I. R. (2001) J. Phys. Chem. B, 105: 7280-7290.
The study of physical and chemical properties at nanoscale hybrid inorganic-organic interfaces is an emerging area of scientific research. Very rich electrical and optical phenomena have been observed at such nanoscale hybrid interfaces. Research in our group is focused on the self-assembly, modification, and characterization of hybrid interfaces for applications in sensors, energy storage and conversion, molecular electronics, and solid-state lighting. For example, as shown below in Figure 1, we used gas-induced changes in the electrical transport properties of a percolating nanocluster-like palladium thin film on a self-assembled organic monolayer to rapidly detect hydrogen and other gaseous species.
Figure 1. Schematic drawing of a nanopalladium thin film/organic monolayer assembly used in the rapid detection of hydrogen. Conductivity is low in the absence of hydrogen, but higher when hydrogen is present.
We also synthesize aligned nanostructures--including nanowires, nanotubes, and nanodots--with controlled sizes and shapes. We use nanoporous materials such as anodized aluminum oxide (AAO) as templates for these syntheses, and explore novel biological and energy-related applications based on these nanoarchitectured materials. An example of one such nanostructured material is shown in Figure 2, below.
Through our close and active collaborations with researchers at Argonne National Laboratory, students in our group will use a variety of cutting-edge techniques, including atomic force microscopy, scanning electron microscopy, UHV thin-film sputter systems, thermal evaporation, photo/electron-beam lithography, and transport measurement systems to explore the fundamental science of nanoscale hybrid interfaces and materials.
Figure 2. Atomic force microscopy image of a hexagonally ordered array of alumina nanopores fabricated by anodization in 0.3 M oxalic acid at 10 °C, viewed from the top. (From Xu, Zangari and Metzger, Nano Lett., 2002, 2: 37.)