One of the main challenges that mankind has to face is the reduction of greenhouse gas emissions. Therefore, it is crucial to develop alternative renewable energy sources. One potential route passes through the splitting of water to release oxygen and hydrogen. Metal-dithiolene complexes have shown to be an effective class of electrocatalysts for the hydrogen evolution reaction (HER). Dithiolene ligands feature properties that include non-innocent behavior for electron storage, S-centers poised for H+shuttling, and functionality that can be tuned for catalysis.Here we report on the mechanism for the electrocatalytic generation of hydrogen from weak acids using cobalt-dithiolene complexes. The starting material is dimeric, and initial reductions yield monomeric species. Our density functional theory (DFT) calculations seem to clarify issues such as metal-centered vs ligand-centered reduction and metal vs sulfur protonation. Calculations show that electrocatalysis occurs via initial formation of a cobalt-hydride intermediate from which further reduction accompanied by protonation of the sulfur atom releases H2. A transition state for this last step was located and suggests that H2 elimination proceeds through the formation of a cobalt dihydrogen species.

Understanding the electronic structure of cobalt-dithiolene H<sub>2</sub> evolution catalysts

248th National Meeting (2014)

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Understanding the electronic structure of cobalt-dithiolene H2 evolution catalysts

Understanding the electronic structure of cobalt-dithiolene H₂ evolution catalysts