A Computational Study of the Mechanism of Hydrogen Evolution by Cobalt(Diimine‐Dioxime) Catalysts. Issue 45 (17th September 2013)

• Record Type: Journal Article
• Authors: Bhattacharjee, Anirban; Andreiadis, Eugen S.; Chavarot‐Kerlidou, Murielle; Fontecave, Marc; Field, Martin J.; Artero, Vincent
• Is Part Of: Chemistry. Volume 19:Issue 45(2013)
• Page Start: 15166
• Page End: 15174
• Publication Date: 2013-09-17
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201301860
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Cobalt(diimine‐dioxime) complexes catalyze hydrogen evolution with low overpotentials and remarkable stability. In this study, DFT calculations were used to investigate their catalytic mechanism, to demonstrate that the initial active state was a Co^I complex and that H₂ was evolved in a heterolytic manner through the protonation of a Co^IIhydride intermediate. In addition, these catalysts were shown to adjust their electrocatalytic potential for hydrogen evolution to the pH value of the solution and such a property was assigned to the presence of a H⁺‐exchange site on the oxime bridge. It was possible to establish that protonation of the bridge was directly involved in the H₂‐evolution mechanism through proton‐coupled electron‐transfer steps. A consistent mechanistic scheme is proposed that fits the experimentally determined electrocatalytic and electrochemical potentials of cobalt(diimine‐dioxime) complexes and reproduces the observed positive shift of the electrocatalytic potential with increasing acidity of the proton source.</p> </abstract>