Standardized Characterization of Electrocatalytic Electrodes

Abstract

This paper investigates the utility of cross -lab comparative analysis of electrocatalytic electrode performance using standardized modular stack cells and test protocols. Using poly(methylene green)-modified glassy carbon electrodes as the model system, we characterized electrode fabrication and performance with respect to the catalytic oxidation of NADH at neutral pH and low overpotential. Three sets of experiments were duplicated across four independent laboratories and the experimental results from each set were analyzed and compared in terms of key electroanalytical parameters. Statistical analyses were performed at three distinct levels: 1) the standard deviation among repetitive cycles within an experiment; 2) the standard deviation among repetitive experiments in the same laboratory, and 3) the standard deviation among experiments performed across all four laboratories. Using predefined criteria of reproducibility for each level, most parameters were found to be statistically reproducible at most levels. When a particular parameter was found to be irreproducible in a given level, commentary is given on how that information can be used diagnose what chemical/physical aspects of the process were uncontrolled or poorly understood and therefore candidates for future research. This exercise, which is presented as a proof -of-principle step towards the concept of standardizing electrocatalytic evaluation, illustrates the importance of executing electrochemical characterization protocols across several labs and using fixed geometry and dimensions, system configuration, and applied electrochemical conditions. Future work is under way to extend these principles to systems with fluid flow.

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“…[14][15][16] It is a well-characterized NADH electrocatalyst that has not shown typical mediation activity with dehydrogenase enzymes and is used as a model system for this study. 17,18 In this system, the pyruvate is oxidized to acetyl-CoA, while NAD + is reduced to NADH. The NADH then diffuses to the poly͑methylene green͒ layer and is oxidized to regenerate NAD + , while protons cross the Nafion membrane to the cathode and electrons travel through the electronic circuit.…”

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