Lucy Vaughn presenting her research at the Honors Chemistry Symposium

Author: Lucy Vaughn | Major: Biochemistry | Semester: Summer 2024

During the 2024 summer grant term, I worked with my mentors Dr. Stefan Kilyanek and Dr. David Paul, assessing the ability of polymer Nafion to act as a conductive film to trap phosphomolybdic acid (PMA) atop a glassy carbon electrode. My goal is to refine the technique for enclosing PMA on an electrode within a conductive polymer (CP) in order to enhance its water splitting capabilities. As a biochemistry major, I thoroughly enjoy this hands-on lab work with various compounds and machinery. Learning the properties of PMA in a CP film as it acts as a catalyst for water electrolysis will assist in the overall goal of maximizing the efficiency of leveraging polyoxometalates (POMs) – like PMA – in hydrogen generation.

As a sophomore taking Organic Chemistry lab, I met my lab TA Cody Canote, who was a graduate student in Dr. Kilyanek’s lab. He introduced me to Dr. Kilyanek, who presented me the opportunity to work in his lab on the project of suspending phosphomolybdic acid in conductive polymers.

I began research in the Kilyanek lab in the summer 2023 semester, and began studying the effects of solution pH on the redox potentials of PMA. Trials from these studies showed that PMA was easier to reduce in acidic conditions as opposed to basic conditions. During the fall 2023 semester, I studied the ability of PMA to accept protons from water. This study yielded information about the solubility of PMA in water along with useful electron transfer data.

I have worked alongside Dr. David Paul this summer to successfully suspend PMA in Nafion, a conductive polymer used as a film to cover the surface of a glassy carbon electrode. Dr. David Paul has been an immense help in my thesis research; he is extremely knowledgeable in the electrochemistry field and it has been such a blessing to work alongside him for this past year. Dr. Stefan Kilyanek, my thesis mentor, has also been a tremendous help in determining what direction to shift my project in as new challenges arise.

Over the summer, we have been testing out various dilutions of Nafion, and have struggled to find one that fully traps the PMA on to the electrode. In high concentrations of Nafion, the film has cracked, through which the PMA falls through and into the solution. In low concentrations of Nafion, the PMA is barely detectable. We have recently discovered that the air-drying technique we have been using to dry the film is both time-inefficient and contributes to the cracking issue. Drying the film with Nitrogen gas has seemingly eliminated the cracking obstacle, but has not solved the issue of PMA falling through the layer and into the solution.

Our studies have shown significant promise, however. The potentials at which oxygen and hydrogen are reduced are lower with the Nafion/PMA film in pH 1 than they are on the bare electrode in the pH 1 buffer solution (Perchloric Acid). This shows that the film is acting in the desired manner, as a conductor that catalyzes the reduction of hydrogen and oxygen. Thus far, the hydrogen evolution potentials are showing a greater shift with the Nafion/PMA film than the oxygen evolution potentials are. While the overarching goal is to catalyze both reactions, the Nafion is showing promise in being an effective conductor for hydrogen evolution.

For the fall semester, our goal is to eliminate the problems in the film stability and structure – namely the cracking of the films surface and the stability of the PMA in the film. Following this resolution, we will begin to study the efficiency of the Nafion/PMA film in varying pH buffers and ultimately advance to using different CPs – including poly(3,4-ethylenedioxythiophene), polyaniline, polypyrrole, and polyamide – to create other polymer/PMA films in order to weigh the efficiency of each.

Through the course of working on my project in this lab, I have learned to look at unexpected challenges as data rather than as a setback. Very rarely has the PMA behaved as ideally as predicted, which often leads to tedious testing to identify the problem. Though the lab work can be difficult to interpret at times, it has been a great blessing to have so many instances to learn from.

The Honors College Research Grant has allowed me the flexibility to continue my studies on this topic that has quickly become a great academic interest and pursuit of mine. I have learned about the promising properties of phosphomolybdic acid as a water electrolysis catalyst and am eagerly looking forward to continuing my studies with the assistance of the Honors College Research Grant over the upcoming fall 2024 semester. I am incredibly grateful for the opportunities I have been graciously presented with by Dr. Kilyanek and Dr. Paul and for the support of the Honors College in my endeavors.