2025 AIChE Annual Meeting

(197f) Maximizing Formic Acid Electro-Oxidation Via Potentiodynamic Modeling

Authors

Omar Abdelrahman, University of Massachusetts Amherst
Lars Grabow, University of Houston
Formic acid (FA) is increasingly recognized as an attractive energy carrier due to its high volumetric energy density, minimal toxicity, low flammability, and facile hydrogen release through oxidation at ambient conditions, making it suitable for direct formic acid fuel cells (DFAFC). However, the practical implementation of FA electro-oxidation is impeded by intrinsic kinetic limitations and mass transport issues. Recent experimental findings highlight dynamic electrode potential modulation as a promising strategy to enhance catalytic performance beyond conventional steady-state limits [1].

Using detailed kinetic sensitivity analyses and dynamic computational modeling, our study confirms that carefully engineered potential cycling significantly improves the cycle-averaged turnover frequency (TOF) for formic acid oxidation on platinum electrodes compared to steady-state conditions. By minimizing mass transport limitations in highly acidic environments, intrinsic kinetic mechanisms and reaction pathway dynamics are clearly identified.

Our results illustrate a distinct potential-dependent surface environment at steady state: at lower potentials, FA dehydration is favorable, resulting in substantial CO surface coverage; at elevated potentials, dehydrogenation without breaking CO bonds becomes dominant resulting in a high bidentate formate coverage, ultimately poisoning the surface at high potentials. Dynamic modulation strategically circumvents steady state constraints and exploits access to intermediate surface coverages. By dynamically traversing different coverages and kinetically limited regimes, the reaction reaches transient rates that substantially exceed steady-state catalytic performance.

Furthermore, optimal modulation of parameters—such as cycling frequency, amplitude, and potential profile—are identified to maximize catalytic efficiency and energy conversion. Integrating fundamental mechanistic insights with practical dynamic modulation strategies represents a significant advancement toward viable formic acid-based electrochemical energy technologies, promising transformative benefits for sustainable energy conversion.

References:

[1] Gopeesingh, J., Ardagh, M. A., Shetty, M., Burke, S. T., Dauenhauer, P. J., Abdelrahman, O. A. (2020). ACS Catalysis 10(17), 9932–9942.