'Holey' graphene for energy storage
Rajaram Narayanan/Jacobs School of Engineering/UC San Diego
How it's made
Making a perfect carbon nanotube structure - one without defects, which are holes corresponding to missing carbon atoms -- is next to impossible. Rather than avoiding defects, the researchers in Bandaru's lab figured out a practical way to use them instead.
"I was motivated from the point of view that charged defects may be useful for energy storage," said Bandaru.
The team used a method called argon-ion based plasma processing, in which graphene samples are bombarded with positively-charged argon ions. During this process, carbon atoms are knocked out of the graphene layers and leave behind holes containing positive charges -- these are the charged defects. Exposing the graphene samples to argon plasma increased the capacitance of the materials three-fold.
"It was exciting to show that we can introduce extra capacitance by introducing charged defects, and that we could control what kind of charged defect we could introduce into a material," said Rajaram Narayanan, a graduate student in professor Bandaru's research group and first author of the study.
Using Raman spectroscopy and electrochemical measurements, the team was able to characterize the types of defects that argon plasma processing introduced into the graphene lattices. The results revealed the formation of extended defects known as "armchair" and "zigzag" defects, which are named based on the configurations of the missing carbon atoms.
Additionally, electrochemical studies helped the team discover a new length scale that measures the distance between charges. "This new length scale will be important for electrical applications, since it can provide a basis for how small we can make electrical devices," said Bandaru.
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Investigation with spectroscopy gives us unique insights into the composition and structure of materials. From UV-Vis spectroscopy to infrared and Raman spectroscopy to fluorescence and atomic absorption spectroscopy, spectroscopy offers us a wide range of analytical techniques to precisely characterize substances. Immerse yourself in the fascinating world of spectroscopy!
Topic World Spectroscopy
Investigation with spectroscopy gives us unique insights into the composition and structure of materials. From UV-Vis spectroscopy to infrared and Raman spectroscopy to fluorescence and atomic absorption spectroscopy, spectroscopy offers us a wide range of analytical techniques to precisely characterize substances. Immerse yourself in the fascinating world of spectroscopy!