Issue 48, 2018

Reactivity and energy level of a localized hole in liquid water

Abstract

We study the reactivity and the energy level associated with the reduction of the H2+ radical cation in liquid water by combining ab initio molecular dynamics simulations at the hybrid functional level, a grand-canonical formulation of solutes in aqueous solution, and nudge-elastic-band calculations. We demonstrate that this extremely oxidative solute promptly dissociates and calculate an energy barrier for the reaction of 0.06 eV, consistent with the short measured lifetimes. We calculate the energy level related to the H2+/H2O redox couple with respect to the vacuum level and to the computational standard hydrogen electrode (SHE), using the thermodynamic integration method. This energy level is found to lie at 3.8 ± 0.1 eV above the SHE level, in remarkable agreement with a previous estimate based on thermodynamical data. The implications of the present results for the mechanism of water splitting at the heterogenous semiconductor–water interface are discussed.

Graphical abstract: Reactivity and energy level of a localized hole in liquid water

Article information

Article type
Paper
Submitted
11 Jun 2018
Accepted
14 Nov 2018
First published
22 Nov 2018

Phys. Chem. Chem. Phys., 2018,20, 30281-30289

Reactivity and energy level of a localized hole in liquid water

F. Ambrosio and A. Pasquarello, Phys. Chem. Chem. Phys., 2018, 20, 30281 DOI: 10.1039/C8CP03682A

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