Date of Award

5-18-2019

Document Type

Thesis

Degree Name

Bachelor of Science (BS)

Department

Chemistry and Biochemistry

First Advisor

Richard Schaeffer

Abstract

The oxygen reduction reaction is particularly relevant in its application in hydrogen fuel cells. As of now, platinum is the most effective catalyst for this reaction, but it is rare and expensive. If a less expensive material could be found with comparable catalytic efficiency to platinum, hydrogen fuel cells would become more accessible as a commercial technology. Recently, nitrogen-doped graphene or graphite has been explored as a more affordable substitute for platinum in hydrogen fuel cells. In this project we explore films of carbon nitride to determine the extent of its electrochemical activity. Carbon nitride films were deposited on commercially-available screen-printed graphite electrodes by direct current magnetron sputtering, a physical vapor deposition method. The samples produced by these methods were analyzed for oxygen reduction by cyclic voltammetry (CV) in an aqueous KOH solution saturated with O2, and physically characterized by x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). We found that the catalytic activity of the carbon nitride films was optimized when deposited in a higher-pressure plasma with a lower proportion of N2 to Ar. Though the optimal carbon nitride films were still inferior to platinum electrodes, they did improve significantly upon pure carbon films—more than 80% of the difference in catalytic activity between carbon films and platinum—despite an amorphous crystal structure. However, it is possible that some of this difference in performance is due to increased roughness in the carbon nitride films; the data are unclear. We predict that sputtered carbon nitride films could be comparable to platinum if deposited to be more graphitic (i.e. more ordered).

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