Rate Enhancement and Energy Efficiency of Applied Potential Oscillations During Formic Acid Electro-oxidation
Year: 2026
Type: dissertation
Abstract: Catalysis is a rapidly evolving field that requires the continuous search for new and sustainable catalysts that involve developing new materials, which can be expensive and time-consuming. Addressing these challenges, dynamic catalysis emerges as an innovative field that overcomes limitations by employing potential modulation to achieve higher rates, surpassing the static Sabatier maximum. This is realized by providing elementary steps—adsorption, reaction, and desorption—with the energetic environment required to optimize overall catalytic turnover. Formic acid has gained interest due to serving as a hydrogen storage, and the electro-oxidation of formic acid over platinum, an extensively studied chemistry with well-defined mechanisms, serves as a model chemistry to investigate the thermodynamic properties and energetic costs of dynamic systems. Kinetic data reveals that, under various oscillation frequencies, the rate of CO2 formation exceeds the static Sabatier maximum by approximately 20 times, observed at 0.6 V vs NHE. This investigation seeks to enhance our understanding of how applied oscillations influence CO2 formation rates and potential energetic costs. Experiments involved applying potential oscillations in square-wave form from 0 V to 0.8 V vs. NHE to understand the impact of oscillation timescale and formic acid concentration on the rate. Results indicate that adjusting the fraction of time spent at each potential, while maintaining a frequency of 1 Hz, maximizes the rate at a duty cycle of 95%, surpassing rates obtained at the highest frequency of 10 Hz. Additionally, reaction order studies demonstrate a decrease in the reaction order concerning formic acid concentration with increasing potential oscillation frequency. Analyzing energetic costs, correlations were established using fundamental thermodynamic concepts to examine faradaic (εFE) and thermodynamic (εTE) efficiency. It was demonstrated that applied potential oscillations do not significantly impact faradaic efficiency, maintaining a 100% faradaic efficiency as expected when varying duty cycle and frequency. Analyzing thermodynamic efficiency, accounting for the charge distribution of the oscillation cycle, reveals comparable efficiency between potentiodynamic and potentiostatic conditions. Establishing thermodynamic and kinetic parity conditions allows for a comprehensive analysis of parameters influencing the implementation of potential oscillations.
DOI: 10.7275/58371
Author: Villariny-Rosado, Faviola
Language: English
Field: Energy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7224886562