(692g) Evaluating Hydrodynamic and Homogeneous Buffer Reaction Effects on the Electrochemical Hydrogen Evolution Reaction Using Experimentally Validated CFD Simulations

The hydrogen evolution reaction (HER) is ubiquitous to aqueous electrochemistry and is often a significant competing reaction that limits the selectivity for desired products. Due to the low onset potentials and numerous proton sources available in aqueous electrochemistry, the range of potentials and reaction rates for many reduction reactions is limited to maintain desirable selectivity. Mass transport effects and contributions of homogeneous buffer reactions can further complicate control over HER selectivity. While bulk properties can be measured, the effect of buffer reactions and hydrodynamics on the region near the electrode surface is difficult to probe experimentally. Alternatively, well parameterized multiscale models can be used to understand how the local environment at the electrode surface can be influenced to control selectivity for HER.

Building on our previous work that successfully captures the hydrodynamics in the rotating cylinder electrode reactor (RCE) [1], we have developed a computational fluid dynamics simulation that captures the experimental behavior of HER in the RCE along with the influence of homogeneous buffer reactions and hydrodynamics. Special considerations in simulating the effects of electrochemical HER with the hydrodynamics and buffer reactions will be discussed along with limitations and challenges associated with accurately simulating the combination of these effects. Results will be discussed in the context of the insights they provide for controlling the local environment at the electrode surface and how the pKa values of the buffer affects the onset of contribution to HER currents on metal electrodes. Finally, the suitability of the RCE for investigating electrochemical reactions will be critically evaluated.

References:

• Richard, D., Tom, M., Jang, J., Yun, S., Christofides, P., Morales-Guio, C., "Quantifying transport and electrocatalytic reaction processes in a gastight rotating cylinder electrode reactor via integration of Computational Fluid Dynamics modeling and experiments," Electrochimica Acta, 440, 141698, 2023.