July 6, 2011
Our internship at the Technical University of Denmark is with the "Catalysis for Sustainable Energy" research initiative. The initiative aims to develop a better understanding of catalytic reactions and use new insights to design cheaper and better catalysts for more efficient use of renewable energy sources, such as sun, wind and biomass. This week marked the beginning of our deposition process for the Nickel Gallium thin films! After many weeks of working with the techniques used in catalysis studies and assisting other researchers in their projects, we began our individual research project. The previous experience has prepared us well.
We worked with our advisor, Christian Damsgaard, to create thin films using a molecular beam epitaxy machine. This evaporates chosen metals onto a substrate of choice using either a high localized temperature, for gallium, or an electron beam gun, for nickel. This operation is done at an extremely low pressure, in the nanobar range, and at an extremely cold surrounding temperature, about 17 Kelvin, so that the metal atoms can flow directly through the chamber with minimal interference.
In our first trial, on Monday, we successfully created a thin film on Pyrex, but we found that the surface was not smooth due to improper cleaning. On Thursday, we conducted a second trial using both Pyrex and a conductive fluorinated tin service. The latter substrate is beneficial for electrochemical tests, which is the ultimate plan for this process. These thin films proved to be much cleaner, yielding a smooth, shimmering surface. Before testing the capabilities of these thin films, they must be characterized while still at their cleanest. X-Ray Diffraction (currently running as I type) allows us to determine the specific nickel gallium alloy created using the x-ray spectrum. While the goal is to create Ni5Ga3, this may not be the case if the metals did not deposit at their desired rates. X-Ray fluorescence allows us to further confirm this data. X-Ray Reflectivity allows us to determine the thickness of the film; atomic force microscopy allows us to determine the surface roughness; and the scanning electron microscope gives a greater insight into the specific structure of the alloy surface.
All of these techniques are essential because the surface structure, roughness, and composition are the elements that make a good catalyst. We need to know this data prior to testing so the structure is reproducible. Next week, these thin films will be electrochemically tested to determine their catalytic abilities for methanol synthesis or carbon dioxide reduction. Both of these production processes are already in use, but they are currently inefficient and use both rare and costly catalysts, such as platinum. The goal is to move towards a more available catalyst that can provide the same reaction using much less power. This research is vital because it looks to make fuel production from a source more sustainable than oil, in this case carbon dioxide, with not only a lower environmental impact, but possibly a positive one as well.
We have also had a wonderful time exploring other renewable energy applications in Copenhagen and surroundings.