(532af) Beyond Tafel Fitting for Kinetic Analysis of Electrochemical CO2 Reduction

Electrochemical carbon dioxide (CO₂) reduction, in which waste CO₂ and water are converted into higher value chemicals desirable for a wide range of applications using renewable energy, will be critical to achieving a sustainable future. Developing a novel catalyst with high efficiency and selectivity is critical to optimizing modern electrochemical CO₂ reduction devices. An important figure of merit in characterizing the efficacy of a catalyst and analyzing current-voltage behavior of these devices is the Tafel slope, defined as the amount of overpotential needed to increase the current by a factor of ten. However, common methods for determining the Tafel slope involve a large degree of subjectivity and face limitations due to substantial data insufficiency commonly associated with product quantification. The limitations of current Tafel fitting methods motivate our overall objective to couple modern data analysis with multiphysics modeling to calculate kinetic parameters for CO₂ reduction.

Herein, we present a robust fitting procedure that leverages modern data science techniques and multiphysics modeling to calculate kinetic parameters with a defined uncertainty threshold. This algorithm was used to extract kinetic parameters from a wide range of data reported in the literature and to establish the distribution of values obtained and the extent of their correlation. We also assessed whether Tafel slopes converge to values commonly associated with known microkinetic steps derived from first principles (i.e., cardinal values). Ultimately, this work provides a methodology that can be applied to various device architectures and reaction chemistries in order to extract rate parameters for individual products with greater rigor and standardization.