The use of Tafel plots for the analysis and benchmarking of heterogeneous catalysts used in water splitting is prevalent and generally useful. Tafel plots allows for a visual summary of some key thermodynamic and kinetic characteristics of electrocatalysts, giving insight into catalytic rates and possible rate determining steps for the catalytic mechanism. No analogous analysis is available for the plethora of homogeneous catalysts developed for water splitting. Often a single chemical oxidant or reductant is used in homogeneous studies to yield an average turnover rate. Interpretation of this turnover rate is then wholly dependent on the particular conditions of the experimental conditions employed. The most practical issue that results is the inability to accurately compare the catalytic performances of various homogeneous catalysts with each other, as well as with other heterogeneous catalysts. In addition, the construction of a Tafel plot for a given catalyst would give key insights that, coupled with other kinetic studies, allows us to construct a more accurate catalytic mechanism. In our study, we use a series of stopped-flow kinetic experiments in addition to more traditional electrochemical analyses to construct a model that relates the thermodynamic and kinetic behavior of a few different molecular water oxidation catalysts <i>à la</i> Tafel plots. From there, we look at the information gained from such an approach, its limitations and broader implications for catalyst research in water splitting.

Constructing and analysis of Tafel plots for homogeneous water oxidation catalysts

2019 Fall National Meeting

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