Electrochemical Mechanistic Analysis from Cyclic Voltammograms Based on Deep Learning.

For decades, employing cyclic voltammetry for mechanistic investigation has demanded manual inspection of voltammograms. Here, we report a deep-learning-based algorithm that automatically analyzes cyclic voltammograms and designates a probable electrochemical mechanism among five of the most common ones in homogeneous molecular electrochemistry. The reported algorithm will aid researchers' mechanistic analyses, utilize otherwise elusive features in voltammograms, and experimentally observe the gradual mechanism transitions encountered in electrochemistry. An automated voltammogram analysis will aid the analysis of complex electrochemical systems and promise autonomous high-throughput research in electrochemistry with minimal human interference.

Homogeneous molecular catalysis of the electrochemical reduction of N2O to N2: redox vs. chemical catalysis.

Homogeneous electrochemical catalysis of N2O reduction to N2 is investigated with a series of organic catalysts and rhenium and manganese bipyridyl carbonyl complexes. An activation-driving force correlation is revealed with the organic species characteristic of a redox catalysis involving an outer-sphere electron transfer from the radical anions or dianions of the reduced catalyst to N2O. Taking into account the previously estimated reorganization energy required to form the N2O radical anions leads to an estimation of the N2O/N2O˙- standard potential in acetonitrile electrolyte. The direct reduction of N2O at a glassy carbon electrode follows the same quadratic activation driving force relationship. Our analysis reveals that the catalytic effect of the mediators is due to a smaller reorganization energy of the homogeneous electron transfer than that of the heterogeneous one. The physical effect of "spreading" electrons in the electrolyte is shown to be unfavorable for the homogeneous reduction. Importantly, we show that the reduction of N2O by low valent rhenium and manganese bipyridyl carbonyl complexes is of a chemical nature, with an initial one-electron reduction process associated with a chemical reaction more efficient than the simple outer-sphere electron transfer process. This points to an inner-sphere mechanism possibly involving partial charge transfer from the low valent metal to the binding N2O and emphasizes the differences between chemical and redox catalytic processes.