We present a theoretical investigation of the H2 oxidation�production mechanism catalyzed by the [Ni(P2N2)2]2+ class of molecular electrocatalysts. An important step in this mechanism involves electrochemical reduction of the Ni complex and proton transfer between an amine ligand N and the Ni center. This step could be sequential electron-proton transfer, with either the proton or electron transferring first, or concerted electron-proton transfer (EPT). The EPT mechanism may be favorable because it could avoid high-energy intermediates. We study these mechanisms within a Marcus theory framework extended to electrochemical EPT. We calculate the driving forces and reorganization energies, as well as the rate constants as functions of overpotential, for the EPT and electron transfer reactions. These results illustrate that the EPT rate constant will increase as the equilibrium Ni�N distance decreases and as the pendant amines become more flexible to facilitate decreasing this distance with a lower energy cost.

Molecular electrocatalysts for H<sub>2</sub> oxidation and production: Proton-coupled electron transfer mechanisms

244th National Meeting (2012)

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Molecular electrocatalysts for H2 oxidation and production: Proton-coupled electron transfer mechanisms

Molecular electrocatalysts for H₂ oxidation and production: Proton-coupled electron transfer mechanisms