Marjorie A. Langell
Charles Bessey Professor
Hamilton Hall 629
402.472.2702
mlangell@unlserve.unl.edu
Langell Research Group
Faculty & Research | Faculty Directory | Recent Publications
Current Research
Research in our group focuses on the surface chemistry of transition metal oxides (TMOs), with applications to material science, heterogeneous catalysis and nanotechnology. The TMO-gas adsorbate interaction represents a particularly influential aspect of surface oxide characteristics, and we are studying the redox properties of iron, nickel and cobalt oxides and their reactivity toward water, carboxylic acids and other oxygen-containing molecules. In surface chemistry, we must be able to obtain information predominately from only the outermost few atomic layers of a solid. To do this, we need to use a number of analytical surface-sensitive techniques to obtain information on the composition, structure and reactivity of the TMO surface. One such technique is x-ray photoelectron spectroscopy, or XPS, shown to the right.
Under-coordinated defects are prime sites for adsorption at TMO surfaces. We are modeling oxide defects experimentally by creating vicinally-stepped substrates, cut at a small angle from a stable, close-packed plane to show a "staircase" structure of periodic terraces separated by atomic-level steps. By correlating surface reactivity with terrace width, we are able to correlate the surface reactivity with defect density. Results indicate that stepped NiO(100) surfaces are more active in adsorption and also can interact with the molecule through an altered bonding configuration. In addition to experimental measurements on structure, composition and reaction kinetics, we are modeling the stepped surface stability and surface-adsorbate complex with Crystal and Gaussian computational techniques.
Interdisciplinary research projects are available in collaborative ventures to address the magnetic aspects of ZnxNi1-xO and CuxNi1-xO mixed-metal oxides, and in the surface-mediated remediation of ground water and soils with graphite, zero-valent iron and other substrates that show activity in the deactivation of halocarbons, nitrates and other environmental pollutants.
- surface science
- transition metal oxides
- surface electronic and magnetic properties
- vicinally-stepped oxide surfaces
- gas adsorption and heterogeneous catalysis
- computational modeling of gas-substrate interactions
- XPS, AES, SIMS, HREELS, LEED, AFM and TDS techniques
- metal-oxide assisted environmental remediations
A graduate or postdoctoral student in my group can expect to receive training in surface science and ultrahigh vacuum technology and significant exposure to one or more of the following specialties: surface analytical chemistry, heterogeneous catalysis, photoemission, electron diffraction, computational chemistry, TMO nanoparticle fabrication and solid state TMO synthesis.
